arXiv subjects

Suveen Mathaudhu

Publications and source records attributed to Suveen Mathaudhu.

3 recordsLinked to original sources

arXiv2024

Prediction of defect properties in concentrated solid solutions using a Langmuir-like model

The alleged existence of sluggish diffusion in high entropy alloys has drawn controversy. In high entropy alloys, and in general in all solids, transport properties are controlled by point defect concentration, which must be known before performing atomistic simulations to compute transport coefficients. In this work, we present a general Langmuir-like model for defect concentration in an arbitrarily complex solid solution and apply this model to generate expressions for concentrations of vacancies and small interstitial atoms. We then calculate the vacancy concentration as a function of temperature in the equiatomic CoNiCrFeMn and FeAl alloys with modified embedded-atom-method potentials for various chemical orderings, showing there is no clear correlation between vacancy thermodynamics and chemical ordering in the CoNiCrFeMn alloy but clear systematic patterns for FeAl. We believe this is due to the high stability of disordered, random and ordered, intermetallic phases respectively in the CoNiCrFeMn and FeAl systems. This work provides future avenues to the prediction of thermal interstitials and vacancies in solid solutions, which is necessary for models of non-equilibrium behavior of solid solutions.

cond-mat.mtrl-sci↗

arXiv2021

Electrical conductivity characterized at varying strains in spiral cut high-pressure torsion discs

High-pressure torsion (HPT) imparts inhomogeneous strain to process discs with low strain in the center and higher strain at the outer edge. Microscopy and microhardness indentation have been used to characterize and correlate this inhomogeneity with strain, but similar exploration with other properties has been uncommon. In this work, the electrical conductivity of pure copper discs processed by HPT was characterized with respect to equivalent strain by cutting them into spirals with an incremental, monotonic increase in strain. Electrical conductivity varied with straining in agreement with the literature and expectations based on grain boundary evolution. The spiral conductivity testing method outlined in this work can improve characterization of HPT materials in future studies.

physics.app-ph↗

arXiv2021

Strain effects on the wear rate of severely deformed copper

A variety of severe plastic deformation (SPD) techniques have been developed to process materials to high strains and impart microstructural refinement. High pressure torsion (HPT) is one technique that imparts inhomogeneous strain to process discs with low strain in the center and high strain at the outer edge. In the literature, this inhomogeneity is typically ignored when characterizing wear properties after HPT. In this work, the wear rate of pure copper discs processed by HPT was characterized by conducting dry sliding reciprocating wear tests at a few judicious locations on the discs. From only two discs, the wear resistance across many ranges of strains was captured. These measurements agreed with the literature for other SPD processes at varying strains. Wear rates dropped and plateaued at about 25% that of the unprocessed state when processing past equivalent strains of around 15, after which microstructural and microhardness saturation has also been observed. Some indication of a relationship between the direction of the imposed SPD shearing and the sliding wear direction was also observed. The incremental microstructure, microhardness, and wear resistance evolution past equivalent strains of ~15 indicate that for high purity copper these properties receive no clear benefit from higher SPD strains.

physics.app-ph↗