Effect of FeCoNiMnCr High-Entropy Alloy Reinforcement on Mechanical, Wear, and Thermal Expansion Behavior of Copper Matrix Composites

Abstract

High-entropy alloys (HEAs) are being considered as potential reinforcements in metal matrices to overcome limitations exhibited by ceramic reinforcements. In the present work, FeCoNiMnCr HEA-reinforced copper matrix composites were fabricated through powder metallurgy and investigated for their mechanical, wear, and thermal expansion behaviors. Elemental powders of Fe, Cr, Ni, Mn, and Co were mechanically alloyed in a high-energy ball mill for 15 h to obtain single-phase FCC-structured FeCoNiMnCr HEA powders. These milled HEA and Cu powders were proportionately blended for required compositions (0 wt.%, 2.5 wt.%, 5 wt.%, and 10 wt.% HEA), subsequently compacted at 700 MPa and sintered at 900 °C in an Ar atmosphere to produce Cu-HEA composites. The microstructure of the FeCoNiMnCr HEA and the Cu-HEA composites were studied using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The micro-hardness and compressive strength of Cu-10% HEA were 40% and 60% more than pure Cu, respectively. Cu-HEA composites showed reduced specific wear rates and COF values as compared to the pure Cu matrix. The co-efficient of thermal expansion (CTE) curves of the Cu-HEA composites were similar to that of pure Cu due to low thermal mismatch between the HEA reinforcement and the Cu matrix, resulting in a reduction of thermal stresses.