Tribological behaviour of AZ31 magnesium alloy reinforced by bimodal size B4C after precipitation hardening

This study investigated dry sliding wear properties of AZ31 magnesium alloy and B4C-reinforced AZ31 composites containing 5, 10, and 20 wt.% B4C with bimodal sizes under different loadings (10-80 N) at various sliding speeds (0.1-1 m/s) via the pin-on-disc configuration. Microhardness evaluations showed that when the distribution of B4C particles was uniform the hardness of the composites increased by enhancing the reinforcement content. The unreinforced alloy and the composite samples were examined to determine the wear mechanism maps and identify the dominant wear mechanisms in each wear condition and reinforcement content. For this purpose, wear rates and friction coefficients were recorded during the wear tests and worn surfaces were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry analyses. The determined wear mechanisms were abrasion, oxidation, delamination, adhesion, and plastic deformation as a result of thermal softening and melting. The wear evaluations revealed that the composites containing 5 and 10 wt.% B4C had a significantly higher wear resistance in all the conditions. However, 20 wt.% B4C/AZ31 composite had a lower resistance at high sliding speeds (0.5-1 m/s) and high loadings (40-80 N) in comparison with the unreinforced alloy. The highest wear resistance was obtained at high sliding speeds and low loadings with the domination of oxidative wear.(c) 2021 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ) Peer review under responsibility of Chongqing University

Automated summary

This study investigated the dry sliding wear properties of AZ31 magnesium alloy and B4C-reinforced AZ31 composites with bimodal sizes. The results showed that the hardness of the composites increased with the reinforcement content when the distribution of B4C particles was uniform. The composites with 5 and 10 wt.% B4C exhibited significantly higher wear resistance in all conditions, while the composite with 20 wt.% B4C had lower resistance at high sliding speeds and high loadings. The highest wear resistance was observed at high sliding speeds and low loadings, with oxidative wear as the dominant mechanism.