Micro-mechanical properties study of high pressure synthesized substances

Tao Liang ^1,*

1. Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, China

Abstract
      Mechanical properties characterization is essential for the potential exploration and structural research of high-pressure synthesized substances. In addition to determining the fundamental mechanical parameters through characterization, understanding the microscopic mechanical mechanisms during deformation could also help for describing the structural characteristics.[1] Exceptional mechanical properties optimized by high-pressure treatment, such as ultra-high hardness, modulus, strength, and toughness, have been always attracting extensive interest in the fields of high pressure physics and materials research.[2-4]
      In the presentation, I will introduce some experimental mechanical and structural researches of high-pressure synthesized samples by using micro-mechanical measurement systems, such as nano-indentation and in-situ SEM micro-pillar compression:
     Continues stiffness measurement (CSM) indenting is used for the mechanical properties measurement of hexagonal silicon (Si-IV, also known as lonsdaleite or wurtzite Si), which phase has attracted considerable research interest due to its extraordinary optical properties and possibility to convert into a direct semiconductor under strain with great potential for applications. The investigation results indicate that the elastic moduli and hardness of Si-IV are close to those of the common diamond cubic silicon.[5]
     Additionally, the energy-tuned La-based MGs are also compared which subjected to annealing, thermal cycling, and high pressure torsion (HPT) treatment in terms of their yield load heterogeneity by using spherical indenter tip mapping. And some in-situ SEM micro-pillar compression studies will also be introduced which are about the gradient structural and mechanical transitions induced by HPT in a high entropy alloy (HEA).

References
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[2] Y. Lin, L. Zhang, H.-k. Mao, P. Chow, Y. Xiao, M. Baldini, J. Shu, W.L. Mao, Amorphous Diamond: A High-Pressure Superhard Carbon Allotrope, Physical Review Letters 2011, 107, 175504.
[3] Q. Huang, D. Yu, B. Xu, W. Hu, Y. Ma, Y. Wang, Z. Zhao, B. Wen, J. He, Z. Liu, Y. Tian, Nanotwinned diamond with unprecedented hardness and stability, Nature 2014, 510, 250-253.
[4] H. Tang, Y. Cheng, X. Yuan, K. Zhang, A. Kurnosov, Z. Chen, W. Xiao, H.S. Jeppesen, M. Etter, T. Liang, Z. Zeng, F. Wang, H. Fei, L. Wang, S. Han, M.-S. Wang, G. Chen, H. Sheng, T. Katsura, Toughening oxide glasses through paracrystallization, Nature Materials 2023, 22, 1189-1195.
[5] T. Liang, L. Xiong, H. Lou, F. Lan, J. Zhang, Y. Liu, D. Li, Q. Zeng, Z. Zeng, Mechanical properties of hexagonal silicon, Scripta Materialia 2022, 220, 114936.