Abstract
The effect of Al content and Si addition on the microstructural and creep properties of Mg–Al–RE alloys was investigated in this study. The steady state creep rates were specified and it was found that the creep behavior of the alloy, which is dependent on the stability of the near grain boundary microstructure, was improved by the RE and Si addition. For the AZ91 alloy, the results indicate a mixed mode of creep behavior, with some grain boundary effects contributing to the overall behavior. However for the RE and Si added samples, sliding of grain boundaries was greatly suppressed and the dislocation climb controlled creep was the dominant deformation mechanism. Analysis of creep rates also showed that the Si addition resulted in formation of Mg 2Si particles (in Chinese Script form) which have a high thermal stability. After Si addition the steady state creep rates were decreased and the creep resistance was improved. This was due to formation of Mg 2Si particles which change the deformation mechanism at elevated temperatures. Addition of cerium rich misch metal to AZ91 alloy resulted in formation of needle shape particles, which also had a very high thermal stability, providing increased creep resistance and superior mechanical properties compared to AZ91 magnesium alloy. As a result, the grain boundaries were less susceptible for grain boundary sliding at high temperatures. By decreasing the Al content of the alloy having 2 wt.% RE from 9 to 4 wt.%, the steady state creep rate was also decreased compared to AZ91 + 2% RE alloy. The fracture mechanism was also investigated and it was observed that although the Si addition improves the creep resistance, it can make the alloy brittle at ambient temperature.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.