Molecular dynamics analysis of nanomachining of rapidly solidified aluminium

Abstract

Rapidly solidified aluminium (RSA) is becoming more recognised as an alternative material to traditional aluminium alloys in the production of optical and structural components. This is due to its improved physical and mechanical properties and ultra-fine microstructure as a result of rapid solidification in the foundry process. The lack of past studies in the molecular dynamics simulation of RSA can be attributed to the lack of sufficient data on the microstructure and interatomic potential limitations. In this paper, an approximation of RSA was modelled to simulate the nanomachining process. The workpiece for the simulation was modelled as an aluminium lattice mixed with the appropriate fractions of the additional elements based on the chemical composition of RSA. The depth of cut was varied from 0.5 to 1.5 nm, and the cutting speed was varied from 5 to 15 m/s. The cutting process was found to be consistent with increase in depth of cut, producing a steady increase in energy, temperature and average cutting forces. Increase in cutting speed produced a slowing increase in energy and temperature while the average cutting forces showed an initial slowing increase followed by a rapid increase. The results showed that cutting speed had a more significant effect on the cutting process that will subsequently affect the desired surface finish. As the surface quality produced in ultra-high precision machining is in the nanoscale, the purpose of this research was to analyse the mechanisms occurring at the subsurface layers and establish a relation to the actual results produced. Experimental evaluations were carried out that agreed with the conclusions made with the MD simulation further proving the eligibility of the MD in nanomachining investigation.