fig2

Figure 2. (A) Schematic diagram of lattice softening caused by mechanical strain; (B) Schematic diagram of ball milling; (C) The speed of sound (v_s) measured by pulse-echo ultrasound versus the internal strain (Cϵ_XRD) as measured. Copyright 2019, Wiley^[28]. (D) Schematic diagram of graphene tensile test; (E) Evolution of the spectra of the 2D under strain. Copyright 2009, Wiley^[51]; (F) Schematic of HPT instrument and method; insert is the picture of the as-processed sample and a schematic of how the stress is introduced; (G) Internal inhomogeneous strain characterization of as-sintered and HPT-processed silicon under 0-1/2 rotation, grain size, and mean strain (Cε) obtained from the analysis. Copyright 2023, Royal Society of Chemistry^[52]. XRD: X-ray diffraction; HPT: high-pressure torsion.