Ductile-Brittle Transition Mechanism of Highly-Oriented 3c-Sic in Elid

Compared with sintered silicon carbides (SiC), highly-orientated 3C-SiC by CVD methods boasts out-of-plane orientation uniformity, which ensures that such materials produce lower surface damage. Through the ELID grinding technique, the differences in grinding behaviors between <110> and <111>-orientated 3C-SiC were investigated. Both highly-orientated 3C-SiC exhibited a grinding surface where brittle and ductile removal coexisted. Specifically, brittle removal regions were observed at grain boundaries, while ductile removal regions were observed within the grains. Further indentation experiments between the two 3C-SiC show that <111>-oriented 3C-SiC displayed a larger critical cut depth of 28.99 nm, with 1.5 times higher than that of <110>-oriented 3C-SiC. The larger critical depth of cut contributes to more ductile removal regions with only a few brittle pits in the <111>-oriented 3C-SiC grinding surface. In addition, the subsurface deformation of <110>-oriented 3C-SiC was characterized by the presence of amorphous zones, dislocations and stacking faults. In contrast to the <111>-oriented, the <110>-oriented 3C-SiC tends to exhibit a brittle removal mode dominated by pits and cracks at the twin boundaries, as its pre-existing twins hinder the dislocation glide, resulting in stress concentration and thus forming cracks.