The effect of deep cryogenic treatment and precipitation hardening on the structure, micromechanical properties and wear of the Mg-Y-Nd-Zr alloy

The paper presents the effect of deep cryogenic treatment (DCT) and a synergic combination of low-temperature treatment and precipitation hardening on the structure, micromechanical and tribological properties of the Mg-Y-Nd-Zr alloy (WE54). Where ageing was preceded by deep cryogenic treatment, a strengthening role of low temperature treatment was found, as well as acceleration of the precipitation process. Tribological tests have shown that both the cryogenic treatment itself and a sequential treatment of the WE54 alloy result in a significant reduction of both tribological wear and the friction coefficient. Examination of wear track morphologies showed the occurrence of abrasive wear mechanisms, such as microploughing and microcutting, as well as the occurrence of materials transfer, which is a typical appearance of the adhesion mechanism. The most advantageous properties were found in the alloy subjected to precipitation hardening using deep cryogenic treatment after solutioning and ageing. The proposed treatment effectively reduced the formation of deep scratches and contributed to an increase in resistance to abrasive wear. The obtained results indicate the possibility of significant improvement in the service life of magnesium alloys with rare earth metals.