# Thermostat Influence on the Structural Development and Material Removal during Abrasion of Nanocrystalline Ferrite

## TL;DR

This study uses molecular dynamics simulations to show that the method of heat removal significantly affects the material removal and structural development during nanomachining of ferrite, highlighting the importance of realistic thermal modeling.

## Contribution

It introduces an electron-phonon coupling based thermostat in MD simulations, providing more accurate temperature gradients and revealing the impact of heat removal mode on nanomachining outcomes.

## Key findings

- Thermostat mode influences grain and chip morphology.
- Average shear stress remains temperature independent up to 1 GPa.
- Heat removal method affects material response beyond 0.4 GPa.

## Abstract

We consider a nanomachining process of hard, abrasive particles grinding on the rough surface of a polycrystalline ferritic work piece. Using extensive large-scale molecular dynamics (MD) simulations, we show that the mode of thermostatting, i.e., the way that the heat generated through deformation and friction is removed from the system, has crucial impact on tribological and materials related phenomena. By adopting an electron-phonon coupling approach to parametrize the thermostat of the system, thus including the electronic contribution to the thermal conductivity of iron, we can reproduce the experimentally measured values that yield realistic temperature gradients in the work piece. We compare these results to those obtained by assuming the two extreme cases of only phononic heat conduction and instantaneous removal of the heat generated in the machining interface. Our discussion of the differences between these three cases reveals that although the average shear stress is virtually temperature independent up to a normal pressure of approximately 1 GPa, the grain and chip morphology as well as most relevant quantities depend heavily on the mode of thermostatting beyond a normal pressure of 0.4 GPa. These pronounced differences can be explained by the thermally activated processes that guide the reaction of the Fe lattice to the external mechanical and thermal loads caused by nanomachining.