The sliding wear behaviour of CoCrFeMnNi and AlxCoCrFeNi high entropy alloys at elevated temperatures

Owing to the reduced defects, low cost, and high efficiency, the additive manufacturing (AM) technique has attracted increasingly attention and has been applied in high-entropy alloys (HEAs) in recent years. It was found that AM-processed HEAs possess an optimized microstructure and improved mechanical properties. However, no report has been proposed to review the application of the AM method in preparing bulk HEAs. Hence, it is necessary to introduce AM-processed HEAs in terms of applications, microstructures, mechanical properties, and challenges to provide readers with fundamental understanding. Specifically, we reviewed (1) the application of AM methods in the fabrication of HEAs and (2) the post-heat treatment effect on the microstructural evolution and mechanical properties. Compared with the casting counterparts, AM-HEAs were found to have a superior yield strength and ductility as a consequence of the fine microstructure formed during the rapid solidification in the fabrication process. The post-treatment, such as high isostatic pressing (HIP), can further enhance their properties by removing the existing fabrication defects and residual stress in the AM-HEAs. Furthermore, the mechanical properties can be tuned by either reducing the pre-heating temperature to hinder the phase partitioning or modifying the composition of the HEA to stabilize the solid-solution phase or ductile intermetallic phase in AM materials. Moreover, the processing parameters, fabrication orientation, and scanning method can be optimized to further improve the mechanical performance of the as-built-HEAs.

https://www.mdpi.com/1099-4300/20/12/937/pdf

Additive Manufacturing of High-Entropy Alloys: A Review.

Effects of normal load and velocity on the dry sliding tribological behaviour of CoCrFeNiMo0.2 high entropy alloy

Towards a greater understanding of serrated flows in an Al-containing high-entropy-based alloy

Tribological behavior of an AlCoCrFeNi2.1 eutectic high entropy alloy sliding against different counterfaces

The tribological properties of Al0.6CoCrFeNi high-entropy alloy with the σ phase precipitation at elevated temperature

Environment can impact the wear behavior of metals and alloys substantially. The tribological properties of Al0.6CoCrFeNi high-entropy alloys (HEAs) were investigated in ambient air, deionized water, simulated acid rain, and simulated seawater conditions at frequencies of 2–5 Hz. The as-cast alloy was composed of simple face-centered cubic and body-centered cubic phases. The wear rate of the as-cast HEA in the ambient air condition was significantly higher than that in the liquid environment. The wear resistance in seawater was superior to that in ambient air, deionized water, and acid rain. Both the friction coefficient and wear rate in seawater were the lowest due to the formation of oxidation film, lubrication, and corrosion action in solution. The dominant wear mechanism in the ambient air condition and deionized water was abrasive wear, delamination wear, and oxidative wear. By contrast, the wear mechanism in acid rain and seawater was mainly corrosion wear, adhesive wear, abrasive wear, and oxidative wear.

Wear behavior of Al0.6CoCrFeNi high-entropy alloys: Effect of environments

A systematic research on the tribological characteristics of Ti48Zr20Nb12Cu5Be15 metallic glass matrix composites was performed under different normal loads in dry condition and simulated seawater. The wear rate decreased with the increase in normal load under dry and simulated seawater conditions. The friction coefficient was lower in the dry condition than in the simulated seawater. The composite showed better wear resistance at lower loads (3, 5 and 10 N) but poor wear resistance at higher loads (15 and 17 N) in the simulated seawater. The analysis of the worn surface illustrated that the wear mechanism in dry condition was plastic deformation, adhesive wear and abrasive wear at 3 and 5 N, while it was abrasive wear and adhesive wear at 10, 15 and 17 N. The wear mechanism in simulated seawater was abrasive wear, plastic deformation and adhesive wear at 3 N, adhesive wear at 10 N, and abrasive wear at 5, 15 and 17 N. At the same time, the corrosion occurred during wear tests in the simulated seawater.

Ming Chen

Papers

The tribological properties of Al0.6CoCrFeNi high-entropy alloy with the σ phase precipitation at elevated temperature

Wear behavior of Al0.6CoCrFeNi high-entropy alloys: Effect of environments

Sliding tribological characteristics of Ti48Zr20Nb12Cu5Be15 metallic glass matrix composites under different conditions

A case of disseminated tb with genitourinary involvement

Adaptive Mixed-Precision Networks