Influence of temperature on the anisotropic cutting behaviour of single crystal silicon: A molecular dynamics simulation investigation

Abstract

Using molecular dynamics (MD) simulation, this paper investigates anisotropic cutting behaviour of single crystal silicon in vacuum under a wide range of substrate temperatures (300 K, 500 K, 750 K, 850 K, 1173 K and 1500 K). Specific cutting energy, force ratio, stress in the cutting zone and cutting temperature were the indicators used to quantify the differences in the cutting behaviour of silicon. A key observation was that the specific cutting energy required to cut the (111) surface of silicon and the von Mises stress to yield the silicon reduces by 25% and 32%, respectively, at 1173 K compared to what is required at 300 K. The room temperature cutting anisotropy in the von Mises stress and the room temperature cutting anisotropy in the specific cutting energy (work done by the tool in removing unit volume of material) were obtained as 12% and 16% respectively. It was observed that this changes to 20% and 40%, respectively, when cutting was performed at 1500 K, signifying a very strong correlation between the anisotropy observed during cutting and the machining temperature.Furthermore, using the atomic strain criterion, the width of primary shear zone was found to vary with the orientation of workpiece surface and temperature i.e. it remains narrower while cutting the (111) surface of silicon or at higher machining temperatures. A major anecdote of 2 the study based on the potential function employed in the study is that, irrespective of the cutting plane or the cutting temperature, the state of the cutting edge of the diamond tool did not show direct diamond to graphitic phase transformation.

An atomistic simulation investigation on chip related phenomena in nanometric cutting of single crystal silicon at elevated temperatures

“…Nevertheless, at temperatures higher than ~1200 K, the chip starts thickening owing to the more pile-up of atoms ahead of the cutting tool due to relatively easier flow of the substrate atoms at high temperatures. However, the cutting force and specific cutting energy keep decreasing as long as the temperature of the substrate is raised [19]. Similar trend was witnessed for the chip height, which has not been shown here.…”

“…Table 1B in Appendix B lists the magnitude of the abovementioned parameters obtained from the simulation data in all the test cases at varying temperatures and crystallographic planes. As shown elsewhere [19] the ABOP potential energy function is robust in predicting forces and fracture stress of silicon. Therefore, the following analysis is carried out based on the results obtained by the ABOP potential.…”

Molecular dynamics simulation investigation on the plastic flow behaviour of silicon during nanometric cutting

“…is the easy cutting direction on the (111) plane of silicon [3,9]. In addition, by comparing the distorted atoms highlighted by grey circles in the Fig.…”

“…The machining temperatures used in this investigation were 300 K, 500 K, 750 K, 850 K, 1173 K and 1500 K which was scaled using the NVE ensemble. To achieve precise results, equilibrium lattice constants were used to perform the simulations [3][4]. A modified variant of the Tersoff interatomic potential function refined by Agrawal et al [5], which is robust in predicting the melting point of silicon and an analytical bond order potential (ABOP) proposed by Erhart and Albe [6], which is robust in accurately describing the mechanical properties of silicon, were adopted in this study.…”

“…Single crystal silicon is a brittle material at ambient temperature due to the sp 3 bonding, relatively short bonding length and closely packed diamond cubic lattice structure, which makes it a difficult-to-machine material.…”