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The Qinling water conveyance tunnel has a large buried depth and high in-situ stress level, and rockburst disasters frequently occurred during excavation. In order to find out the mechanical mechanism of rockburst, the research work in this paper is as follows: (1) In-situ three-dimensional hydraulic fracturing method was used to measure the in-situ stress of the deep buried tunnel crossing the ridge. (2) Based on the measured in-situ stress results, the stress distribution characteristics of the tunnel crossing the ridge were obtained by the multiple linear regression method, and the rockburst tendency during construction was predicted. (3) A three-dimensional numerical model of tunnel excavation was established to analyze the dynamic adjustment characteristics of the surrounding rock stress and elastic strain energy during TBM excavation, and to clarify the mechanical mechanism of rockburst. The research results show that the maximum principal stress of the deep-buried tunnel crossing the ridge of Qinling is 40-66 MPa, which belongs to extremely high in-situ stress level, and medium-strong rockburst may occur during excavation. In the process of TBM excavation, the stress of the surrounding rock in the range of 2.6 times the diameter of the tunnel before and after the working face is adjusted violently, and the concentrated zones after the stress redistribution are mainly distributed in the arch roof and arch bottom, and the stress concentration coefficient can reach 2.06. The arch roof, arch waist, and arch bottom are susceptible to immediate rockburst due to stress transient unloading at the moment of excavation. After the elastic strain energy of the surrounding rock at the arch roof and the arch bottom is released and accumulated, it is easy to cause time delayed rockburst, and the depth of the rockburst pit can reach 3.5 m, which is consistent with the rockburst phenomenon in the field.

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To manufacture metallic components with high wear resistance, treatments such as nitriding and carburising followed by quenching and tempering (NQT and CQT, respectively) are applied to various types of steel to increase the hardness (H) of the friction surface. However, the wear mechanism of the resulting functionally graded materials has not been fully understood. In this study, specimens of industrial 99.82% pure iron treated with NQT at 913 and 1033 K, and CQT at 1203 K, as well as hot-rolled sheets without heat treatment were examined by performing nanoindentation tests to measure changes in their H, reduced Young's moduli (Er), elastic deformation energies (We), and plastic deformation energies (Wp) along the depth direction. The relationship between Wp/We and the elastic strain resistance (H/Er) can be expressed for all specimens via the equation Wp/We = -1.0 + 0.16 (H/Er)-1. Furthermore, the obtained H/Er av measured at 5 µm intervals based on the specimen profile and wear volume has a good correlation depending to the sliding distance, as confirmed by the results of the ring-on-plate sliding tests conducted for the carbon-treated, nitrogen-treated, and hot-rolled specimens. This study provides a new approach, using H/Er parameters to identify the dominant factors affecting wear resistance at the initial stage of wear that may contribute to the development of wear-resistant materials.

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A significant part of the present and future of optoelectronic devices lies on thin multilayer heterostructures. Their optical properties depend strongly on strain, being essential to the knowledge of the stress level to optimize the growth process. Here the structural and microstructural characteristics of sub-micron a-ZnO epilayers (12 to 770 nm) grown on r-sapphire by metal-organic chemical vapour deposition are studied. Morphological and structural studies have been made using scanning electron microscopy and high-resolution X-ray diffraction. Plastic unit-cell distortion and corresponding strain have been determined as a function of film thickness. A critical thickness has been observed as separating the non-elastic/elastic states with an experimental value of 150-200 nm. This behaviour has been confirmed from ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy measurements. An equation that gives the balance of strains is proposed as an interesting method to experimentally determine this critical thickness. It is concluded that in the thinnest films an elongation of the Zn-O bond takes place and that the plastic strained ZnO films relax through nucleation of misfit dislocations, which is a consequence of three-dimensional surface morphology.

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Recent studies have reported the experimental discovery that nanoscale specimens of even a natural material, such as diamond, can be deformed elastically to as much as 10% tensile elastic strain at room temperature without the onset of permanent damage or fracture. Computational work combining ab initio calculations and machine learning (ML) algorithms has further demonstrated that the bandgap of diamond can be altered significantly purely by reversible elastic straining. These findings open up unprecedented possibilities for designing materials and devices with extreme physical properties and performance characteristics for a variety of technological applications. However, a general scientific framework to guide the design of engineering materials through such elastic strain engineering (ESE) has not yet been developed. By combining first-principles calculations with ML, we present here a general approach to map out the entire phonon stability boundary in six-dimensional strain space, which can guide the ESE of a material without phase transitions. We focus on ESE of vibrational properties, including harmonic phonon dispersions, nonlinear phonon scattering, and thermal conductivity. While the framework presented here can be applied to any material, we show as an example demonstration that the room-temperature lattice thermal conductivity of diamond can be increased by more than 100% or reduced by more than 95% purely by ESE, without triggering phonon instabilities. Such a framework opens the door for tailoring of thermal-barrier, thermoelectric, and electro-optical properties of materials and devices through the purposeful design of homogeneous or inhomogeneous strains.

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Objective To analyze the diagnostic value of two-dimensional(2D)ultrasound features combined with ultrasonic elastic strain rate ratio(SR)for breast cancer and discuss their correlations with pathological prognostic indicators.Methods The clinical data of 265 patients with breast cancer admitted to the 2nd Affiliated Hospital of Chengdu Medical College from January 2020 to December 2021 were analyzed retrospectively.Through pathological examination,171 cases were diagnosed with benign lesions(benign group)and 94 cases with malignant lesions(malignant group).The 2D ultrasound and ultrasound elastography imaging data were collected and compared for the two groups in terms of ultrasound appearance and SR.The positive rates of estrogen receptor(ER),progesterone receptor(PR),and proto-oncogene(CerbB-2)were recorded.Receiver operating characteristic(ROC)curve was drawn to analyze the diagnostic efficiency of 2D ultrasound and SR for breast cancer;and Pearman correlation analysis was conducted to assess the correlations between 2D ultrasound features/SR and ER/PR/CerbB-2.Results The 2D ultrasound features such as spicule sign,posterior echo attenuation,microcalcification,lymph node metastasis,and abundant blood flow were more common in malignant group,and the SR was significantly higher than that in benign group(P<0.05).The positive rates of ER,PR and CerbB-2 in malignant group were 59.57%,75.53%and 47.87%,respectively,significantly higher than those in benign group(P<0.05).ROC curve analysis showed that the AUC values of 2D ultrasound,SR,and their combination for breast cancer diagnosis were 0.586,0.743,and 0.761,respectively,indicating a significantly higher diagnostic efficiency of the combined detection than 2D ultrasound or SR alone(P<0.05).The occurrences of spicule sign and posterior echo attenuation and SR were higher in ER-positive patients than in ER-negative patients(P<0.05);lymph node metastasis was more prevalent in PR-positive patients,and their SR was higher than PR-negative patients(P<0.05);CerbB-2 positive patients had more microcalcifications and higher SR value as compared with CerbB-2 negative patients(P<0.05).Pearman correlation analysis revealed that there were positive correlations between 2D ultrasound features such as spicule sign/posterior echo attenuation and ER,lymph node metastasis and PR,microcalcification and CerbB-2,SR and ER/PR/CerbB-2(P<0.05).Conclusion The combination of 2D ultrasound features and SR provides reliable imaging information for the diagnosis of breast cancer.The spicule sign,posterior echo attenuation,lymph node metastasis,microcalcification and SR are correlated to the pathological prognostic indicators(ER,PR,and CerbB-2).

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INTRODUCTION: It has been reported in the literature that Vitamin D can inhibit the growth of uterine fibroids, but the evaluation index is only the size of the uterine fibroids. The purpose of this study was to evaluate the effect of vitamin D on the size, hardness, and blood flow of uterine fibroids in premenopausal women by multimodal ultrasound. METHODS: A total of 64 pre-menopausal women with uterine fibroids complicated vitamin D deficiency were enrolled in this study and randomly divided into two groups: the vitamin D group (n=32) which received oral vitamin D (1600 IU/ day) and the control group (n=32) without vitamin D supplementation. After three months of intervention, the mean diameter of uterine fibroids, elastic strain ratio, and blood flow grade were evaluated by multimodal ultrasound, and the clinical symptoms of the two groups were evaluated by questionnaire. RESULTS: The vitamin D group reported a significant increment in the serum 25-hydroxyvitamin D (P < 0.001). In addition, there were significant reductions in the mean diameter, and elastic strain ratio of uterine fibroids (P =.043 and P =.038, respectively), but no significant difference in the blood flow grade of uterine fibroids was observed (P =.272). Compared with the control group, the vitamin D group achieved significant relief in dysmenorrhea and frequent urination, as well as improvement in heavy menstrual bleeding. CONCLUSION: The application of multimodal ultrasound provides a more comprehensive theoretical basis for vitamin on uterine fibroids. Vitamin D can effectively reduce the size of uterine fibroids in pre-menopausal women and relieve their symptoms. It is highly likely to be a promising, safe, effective, and inexpensive drug for uterine fibroids, which has good application value and promotion prospects.

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We report a new industrial application of aluminum magnesium boride AlMgB14 (BAM) coatings to enhance the hardness of tungsten carbide ceramic (WC-Co) and high-speed steel tools. BAM films were deposited by RF magnetron sputtering of a single dense stoichiometric ceramic target onto commercial WC-Co turning inserts and R6M5 steel drill bits. High target sputtering power and sufficiently short target-to-substrate distance were found to be critical processing conditions. Very smooth (6.6 nm RMS surface roughness onto Si wafers) and hard AlMgB14 coatings enhance the hardness of WC-Co inserts and high-speed R6M5 steel by a factor of two and three, respectively. Complete coating spallation failure occurred at a scratch adhesion strength of 18 N. High work of adhesion and low friction coefficient, estimated for BAM onto drill bits, was as high as 64 J/m2 and as low as 0.07, respectively, more than twice the surpass characteristics of N-doped diamond-like carbon (DLC) films deposited onto nitride high-speed W6Mo5Cr4V2 steel.

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In this work we investigate the Raman response of extremely strained gallium phosphide nanowires. We analyze new strain-induced spectral phenomena such as 2-fold and 3-fold phonon peak splitting which arise due to nontrivial internal electric field distribution coupled with inhomogeneous strain. We show that high bending strain acts as a probe allowing us to define the electric field distribution with deep subwavelength resolution using the corresponding changes of the Raman spectra. We investigate the nature of the localization with respect to nanowire diameter, excitation spot position, and light polarization, supporting the experiment with 3D numerical modeling. Based on our findings we propose a research tool allowing to precisely localize the electric field in a certain subwavelength region of the nanophotonic resonator.

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Stanene, composed of tin atoms, is a member of 2D-Xenes, two-dimensional single element materials. The properties of the stanene can be changed and improved by applying deformation, and it is important to know the range of in-plane deformation that the stanene can withstand. Using the Tersoff interatomic potential for calculation of phonon frequencies, the range of stability of planar stanene under uniform in-plane deformation is analyzed and compared with the known data for graphene. Unlike atomically flat graphene, stanene has a certain thickness (buckling height). It is shown that as the tensile strain increases, the thickness of the buckled stanene decreases, and when a certain tensile strain is reached, the stanene becomes absolutely flat, like graphene. Postcritical behaviour of stanene depends on the type of applied strain: critical tensile strain leads to breaking of interatomic bonds and critical in-plane compressive strain leads to rippling of stanene. It is demonstrated that application of shear strain reduces the range of stability of stanene. The existence of two energetically equivalent states of stanene is shown, and consequently, the possibility of the formation of domains separated by domain walls in the stanene is predicted.

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A novel approach, termed line-rotated remapping (LRR), for high resolution electron backscatter diffraction is proposed to remap patterns with large rotation. In LRR, the displacements during the first-pass cross-correlation is modified to a function of the corresponding Kikuchi lines and the points on the reference pattern. Then, the finite rotation matrix to remap the test pattern to a similar orientation of the reference pattern is determined using the parameters of the Kikuchi lines. We apply LRR to simulated Si patterns with random orientations, and obtain measurement errors below ∼1.0 × 10-3 for lattice rotations up to ∼26°. The maximum angle that may be remapped by LRR decreases with the distance between the specimen and the screen, which in turn reduces the number of matched Kikuchi lines. We also employ LRR in experiments to quantitatively characterize rotations and elastic strains of a Ni single crystal subject to nanoindentation and tension measurements. Although more experimental data on pattern center and image contrast are required to properly assess the performance of LRR, our method is a promising technique to improve strain measurements in the presence of large rotations.

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BACKGROUND: The diffuse sclerosing variant of papillary thyroid carcinoma (DSV-PTC) has ultrasound findings that are similar to Hashimoto's thyroiditis (HT), resulting in under-diagnosis. DSV-PTC combined with HT is also common, so early and accurate diagnosis of DSV-PTC using a variety of diagnostic techniques, including FNAC, BRAFV600E mutation detection, and ultrasound elastography, is critical. OBJECTIVE: To assess the diagnostic value of fine-needle aspiration cytology (FNAC) and BRAFV600E detection in combination with ultrasound elastography in the diagnosis of DSV-PTC. METHODS: We performed a retrospective analysis of 40 patients with pathologically confirmed DSV-PTC and 43 patients with HT admitted to our hospital's ultrasound department between January 2015 and December 2020. Preoperative FNAC, BRAFV600E mutation detection, and ultrasound elastography imaging were all performed on all patients. For a definitive diagnosis, the results of these tests were compared to postoperative pathological findings. The diagnostic value of FNAC, BRAFV600E mutation detection, ultrasound elasticity imaging, and their combination for DSV-PTC diagnosis was assessed. RESULTS: The mean elastic strain rate ratio (E1/E2) of the 40 DSV-PTC cases was 5.75 ± 2.14, while that of the 43 HT cases was 2.81 ± 1.20. The receiver operating characteristic (ROC) curve was generated using the average value of E2/E1. The area under the ROC curve was 0.910, and the optimal E2/E1 cut-off value was 4.500. When FNAC, BRAFV600E mutation detection, and ultrasound elasticity imaging detection were combined, the diagnostic sensitivity, specificity, negative predictive value, positive predictive value, and accuracy of DSV-PTC diagnosis were 92.5%, 95.3%, 93.2%, 94.9%, and 94.0%, respectively, which were significantly higher than the single technique (p < 0.05). CONCLUSIONS: The use of FNAC, BRAFV600E mutation detection, and ultrasound elastography in combination is more helpful in establishing an accurate diagnosis of DSV-PTC than using a single diagnostic technique alone.

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The ladybird beetle (Coccinella septempunctata) is known for swift deployment of its elytra, an action that requires considerable power. However, actuation by thoracic muscles alone may be insufficient to deploy elytra at high speed because the maximum mechanical power that elytral muscles can produce is only 70% of that required for initiation of deployment. Nevertheless, the elytra open rapidly, within 3 ms in the initial phase, at a maximum angular velocity of 66.49±21.29 rad s-1, rivaling the strike velocity of ant lion (Myrmeleon crudelis) mandibles (65±21 rad s-1). Here, we hypothesize that elytra coupling may function as an energy storage mechanism that facilitates rapid opening by releasing elastic strain energy upon deployment. To test this hypothesis and better understand the biomechanics of elytra deployment, we combined micro-computed tomography and scanning electron microscopy to examine the microstructure of the coupling of paired elytra. We found that two rows of setae on the internal edges of the elytra coupling structure undergo elastic deformation when the elytra are locked together. Kinematics observations and mathematical modeling suggest that the elastic potential energy stored in the compressed setae generates 40% of the power required for deployment of elytra. Our findings broaden insights into how ladybirds actuate elytra opening by a strategy of using both muscles and elastic microstructures, and demonstrate a distributed pattern of actuation that adapts to geometrical constraints in elytra locking.

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Conventionally, tuning materials' properties can be done through strategies such as alloying, doping, defect engineering, and phase engineering, while in fact mechanical straining can be another effective approach. In particular, elastic strain engineering (ESE), unlike conventional strain engineering mainly based on epitaxial growth, allows for continuous and reversible modulation of material properties by mechanical loading/unloading. The exceptional intrinsic mechanical properties (including elasticity and strength) of two-dimensional (2D) materials make them naturally attractive candidates for potential ESE applications. Here, we demonstrated that using the strain effect to modulate the physical and chemical properties toward novel functional device applications, which could be a general strategy for various 2D materials and their heterostructures. We then show how ultralarge, uniform elastic strain in free-standing 2D monolayers can permit deep elastic strain engineering (DESE), which can result in fundamentally changed electronic and optoelectronic properties for unconventional device applications. In addition to monolayers and van der Waals (vdW) heterostructures, we propose that DESE can be also applied to twisted bilayer graphene and other emerging twisted vdW structures, allowing for unprecedented functional 2D material applications.

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The occurrence of strain is inevitable for the growth of lattice mismatched heterostructures. It affects greatly the mechanical, electrical and optical properties of nano-objects. It is also the case for nanowires which are characterized by a high surface to volume ratio. Thus, the knowledge of the strain distribution in nano-objects is critically important for their implementation into devices. This paper presents an experimental data for II-VI semiconductor system. Scanning nanobeam electron diffraction strain mapping technique for hetero-nanowires characterized by a large lattice mismatch (>6% in the case of CdTe/ZnTe) and containing segments with nano-twins has been described. The spatial resolution of about 2 nm is 10 times better than obtained in synchrotron nanobeam systems. The proposed approach allows us to overcome the difficulties related to nanowire thickness variations during the acquisition of the nano-beam electron diffraction data. In addition, the choice of optimal parameters used for the acquisition of nano-beam diffraction data for strain mapping has been discussed. The knowledge of the strain distribution enables, in our particular case, the improvement of the growth model of extremely strained axial nanowires synthetized by vapor-liquid solid growth mechanism. However, our method can be applied for the strain mapping in nanowire heterostructures grown by any other method.

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Nanoindentation testing using a Berkovich indenter was conducted to explore the relationships among indentation hardness (H), elastic work energy (We), plastic work energy (Wp), and total energy (Wt = We + Wp) for deformation among a wide range of pure metal and alloy samples with different hardness, including iron, steel, austenitic stainless steel (H ≈ 2600-9000 MPa), high purity copper, single-crystal tungsten, and 55Ni-45Ti (mass%) alloy. Similar to previous studies, We/Wt and Wp/Wt showed positive and negative linear relationships with elastic strain resistance (H/Er), respectively, where Er is the reduced Young's modulus obtained by using the nanoindentation. It is typically considered that Wp has no relationship with We; however, we found that Wp/We correlated well with H/Er for all the studied materials. With increasing H/Er, the curve converged toward Wp/We = 1, because the Gibbs free energy should not become negative when indents remain after the indentation. Moreover, H/Er must be less than or equal to 0.08. Thermodynamic analyses emphasized the physical meaning of hardness obtained by nanoindentation; that is, when Er is identical, harder materials show smaller values of Wp/We than those of softer ones during nanoindentation under the same applied load. This fundamental knowledge will be useful for identifying and developing metallic materials with an adequate balance of elastic and plastic energies depending on the application (such as construction or medical equipment).

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High resolution electron backscatter diffraction is an emerging technique of micro-structural characterization which can be used for local elastic strain measurement. Pattern center (PC) coordinate, an important parameter which affects accuracy of HR-EBSD, should be carefully calibrated before calculation. An integrated digital image correlation (IDIC) algorithm can extract the deformation gradient tensor and return the residual between reference and targeted images simultaneously. We propose to use the residual value as a criterion to calibrate PC, as an accurate PC value, accompanied with sample tilt parameters, results in slightly lower level of residuals when using simulated diffraction patterns. Though the reduction of residual value is small in the calibration process, our experimental dataset shows that the calibrated PC value will reduce the retrieved Von Mises strain, which results from the reduction of phantom strain caused by errors in the initially-guessed PC values given by the commercial software DynamicS.

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A grain is surrounded by grains with different crystal orientations in polycrystalline plain low-carbon steel. The grain is constrained by its adjacent grains in the tension process. The interaction of the grain with the adjacent grains was investigated within the elastic deformation region. The following results have been obtained: (1) the Young's modulus of a grain without consideration of grain-to-grain interaction is denoted as the inherent Young's modulus; when the inherent Young's modulus of a grain is equal to the Young's modulus of the bulk material, there is almost no interaction between the grain and its adjacent grains; when a grain has a great difference between its inherent Young's modulus and the Young's modulus of the bulk material, its grain-to-grain interactions increase significantly; (2) the grain-to-grain interaction is mainly caused by the difference in the inherent Young's modulus between the grain and its adjacent grains; the misorientation angle between the grain and its adjacent grains has almost no effect on the grain-to-grain interaction.

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Challenge 4 of the Air Force Research Laboratory additive manufacturing modeling challenge series asks the participants to predict the grain-average elastic strain tensors of a few specific challenge grains during tensile loading, based on experimental data and extensive characterization of an IN625 test specimen. In this article, we present our strategy and computational methods for tackling this problem. During the competition stage, a characterized microstructural image from the experiment was directly used to predict the mechanical responses of certain challenge grains with a genetic algorithm-based material model identification method. Later, in the post-competition stage, a proper generalized decomposition (PGD)-based reduced order method is introduced for improved material model calibration. This data-driven reduced order method is efficient and can be used to identify complex material model parameters in the broad field of mechanics and materials science. The results in terms of absolute error have been reported for the original prediction and re-calibrated material model. The predictions show that the overall method is capable of handling large-scale computational problems for local response identification. The re-calibrated results and speed-up show promise for using PGD for material model calibration.

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Optical distortions caused by camera lenses affect the accuracy of the elastic strains and lattice rotations measured by high-angular resolution techniques. This article introduces an integrated correction of optical distortions for global HR-EBSD/HR-TKD approaches. The digital image correlation analysis is directly applied to optically distorted patterns, avoiding the pattern pre-processing step conducted so far while preserving the numerical efficiency of the Gauss-Newton algorithm. The correction implementation is first described and its numerical cost is assessed considering a homography-based HR-EBSD approach. The correction principle is validated numerically for various levels of first-order radial distortion over a wide range of disorientation angles (0 to 14°) and elastic strain (0 to 5×10-2). The errors induced when neglecting such distortions as well as the influence of both the radial distortion coefficient and the pattern centre and optical centre locations are quantified. Even when both reference and target patterns are distorted, the correction appears necessary whatever the disorientation between those patterns. The required accuracy on the true distortion parameters for an effective correction is consequently determined.

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Experimental discovery of ultralarge elastic deformation in nanoscale diamond and machine learning of its electronic and phonon structures have created opportunities to address new scientific questions. Can diamond, with an ultrawide bandgap of 5.6 eV, be completely metallized, solely under mechanical strain without phonon instability, so that its electronic bandgap fully vanishes? Through first-principles calculations, finite-element simulations validated by experiments, and neural network learning, we show here that metallization/demetallization as well as indirect-to-direct bandgap transitions can be achieved reversibly in diamond below threshold strain levels for phonon instability. We identify the pathway to metallization within six-dimensional strain space for different sample geometries. We also explore phonon-instability conditions that promote phase transition to graphite. These findings offer opportunities for tailoring properties of diamond via strain engineering for electronic, photonic, and quantum applications.