Isothermal compression bonding mechanism and mechanical properties of WE43 magnesium-rare earth alloy

摘要

Isothermal compression bonding (ICB), or high temperature plastic deformation bonding, has become a prospective solid phase bonding technique without risk of casting defects in the joints compared to the conventional welding. In this study, a rare-earth magnesium alloy is subjected to the ICB process under a range of thermo-mechanical processing parameters. The results show that large grains and low grain orientation spread (GOS) values are observed in the bonding zone at high temperature and low strain rate, which leads to a lower bonding strength but a higher elongation (El). In the other cases (high strain rate or relatively low temperature & low strain rate), the grain size in the bonding zone is refined but the average GOS value increases, resulting in a stronger bonding strength but a weaker El. The former case belongs to a strong grain boundary sliding and thus the metallurgical bonding of the interfacial grain boundaries is enhanced while the latter is a DRX-dominated mechanism by the evaluation of stress exponent and apparent activation energy. In addition, the flow instability criterion is utilized to evaluate whether the ICB process is in a steady condition.