Thermal softening-suppressed inter-granular embrittlement of polycrystalline 3C-SiC under diamond cutting

Numerical simulation of materials-oriented ultra-precision diamond cutting: review and outlook

“…The coordination number for per atom can be identified by the post-processing visualization software OVITO [97]. Correspondingly, the amorphous structure is also found in the subsurface layer adjacent to the machined surface in diamond cutting experiment of 6H-SiC, as shown in figure 5 respectively [41,111,112]. Figures 6(a) and (b) shows the MD simulation and experimental results of subsurface damage of single crystal 6H-SiC in diamond cutting at a DOC of 20 nm, respectively.…”

“…In 1980, MD simulation was utilized for the first time to investigate the cutting mechanism of monocrystalline copper [61]. Recently, the diamond cutting mechanisms of different materials including metallic materials [49,50], hard brittle materials [40][41][42]48], and composite materials [62][63][64] have been extensively investigated through MD simulations. However, MD simulations suffer greatly from the small length scale and time scale that are significantly lower than the natural processes being studied, thus qualitatively predicted results by MD simulations are mainly expected.…”

“…Realizing the ductile-mode cutting is essentially needed to achieve ultra-smooth surface of hard brittle materials, which requires the fundamental understanding of the ductile and brittle deformation mechanisms. Previous studies have demonstrated that the dislocation slip and phase transformation are the two main modes of ductile deformation of hard brittle materials under diamond cutting [40][41][42]. In particular for the high pressure phase transformation, including the amorphization and the structural transformation from the original phase to another crystal phase, acts as one of the dominant mechanisms for the ductile deformation of hard brittle materials in diamond cutting.…”

“…In addition, the atomic tool wear can be significantly suppressed during high temperature cutting [158]. Recently, Zhao et al studied the heat treatmentassisted diamond cutting mechanisms of polycrystalline 3C-SiC by utilizing multiscale modeling and simulation, in which the temperature-dependent properties of GB are derived from MD simulation results of CZM-based tensile/shear loading, and further are used as the input parameters of FE model [41]. In particular, the FE simulation results demonstrate that with the increment of pretreatment temperature, the material removal mode transits from brittle-mode cutting related with inter-granular fracture to ductile-mode cutting related with intra-granular fracture, as shown in figure 12(c).…”

“…Finally, various external energetic fields-assisted diamond cutting processes, such as ultrasonic vibration-assisted [32][33][34], thermal-assisted [35][36][37][38][39][40][41][42] and ion implantationassisted [43][44][45][46][47], have been increasingly employed to promote the ductile machinability of difficult-to-machine materials. While the effectiveness in applying the energetic field assistance for facilitating the critical DOC for brittle-to-ductile (BTD) transition has been well demonstrated, fundamental understanding of the interaction between workpiece material and energetic field is critical for tailoring the field configurations to optimize the energetic field-assisted cutting performance.…”