Anisotropy of single crystal 3C-SiC during nanometric cutting

Goel, Saurav and Stukowski, Alexander and Luo, Xichun and Agrawal, Anupam and Reuben, Robert L (2013) Anisotropy of single crystal 3C-SiC during nanometric cutting. Modelling and Simulation in Materials Science and Engineering, 21 (6). 065004. ISSN 0965-0393

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Abstract

3C-SiC (the only polytype of SiC that resides in a diamond cubic lattice structure) is a relatively new material that exhibits most of the desirable engineering properties required for advanced electronic applications. The anisotropy exhibited by 3C-SiC during its nanometric cutting is significant, and the potential for its exploitation has yet to be fully investigated. This paper aims to understand the influence of crystal anisotropy of 3C-SiC on its cutting behaviour. A molecular dynamics simulation model was developed to simulate the nanometric cutting of single-crystal 3C-SiC in nine (9) distinct combinations of crystal orientations and cutting directions, i.e. (1 1 1) ⟨-1 1 0⟩, (1 1 1) ⟨-2 1 1⟩, (1 1 0) ⟨-1 1 0⟩, (1 1 0) ⟨0 0 1⟩, (1 1 0) ⟨1 1 -2⟩, (0 0 1) ⟨-1 1 0⟩, (0 0 1) ⟨1 0 0⟩, (1 1 -2) ⟨1 -1 0⟩ and (1 -2 0) ⟨2 1 0⟩. In order to ensure the reliability of the simulation results, two separate simulation trials were carried out with different machining parameters. In the first trial, a cutting tool rake angle of -25°, d/r (uncut chip thickness/cutting edge radius) ratio of 0.57 and cutting velocity of 10 m s-1 were used whereas a second trial was done using a cutting tool rake angle of -30°, d/r ratio of 1 and cutting velocity of 4 m s-1. Both the trials showed similar anisotropic variation. The simulated orthogonal components of thrust force in 3C-SiC showed a variation of up to 45%, while the resultant cutting forces showed a variation of 37%. This suggests that 3C-SiC is highly anisotropic in its ease of deformation. These results corroborate with the experimentally observed anisotropic variation of 43.6% in Young's modulus of 3C-SiC. The recently developed dislocation extraction algorithm (DXA) [1, 2] was employed to detect the nucleation of dislocations in the MD simulations of varying cutting orientations and cutting directions. Based on the overall analysis, it was found that 3C-SiC offers ease of deformation on either (1 1 1) ⟨-1 1 0⟩, (1 1 0) ⟨0 0 1⟩, or (1 0 0) ⟨1 0 0⟩ setups.