High Temperature Deformation Behavior of a Newly Developed Mg Alloy Containing Al, Ba and Ca


Newer magnesium alloys that showed promise of high strength and creep resistance are based on Mg-Al-Ba-Ca (ABaX) system. Al, Ba, and Ca are less expensive as alloying elements compared with rare-earth elements and are also flame retarding. ABaX844 is a candidate alloy possessing high creep strength but may pose problems of workability due to heavy alloying. In this study, the deformation characteristics of ABaX844 alloy have been studied using compression tests over a large temperature range of 300 – 500 oC and strain rate range of 0.0003 – 10 s-1 using a 6x6 experimental matrix. The alloy has exhibited two domains for hot working, requiring a minimum temperature of 340 oC and a strain rate of less than 0.2 s-1. Although the strain rate limit is relatively low compared to many other metallic materials, it is similar to the hot working range of other magnesium alloys that are being used currently. The alloy exhibited extensive dynamic recrystallization resulting in a fine-grained microstructure after hot working in these domains, and the binary and ternary intermetallic phases got well distributed at high temperatures. Also, flow instability manifesting as adiabatic shear band and flow localization occurred at strain rates >0.1 s-1. The mechanical properties of the alloy in the typical service temperature range been evaluated, and it is found that the yield strength and ultimate tensile strength are stable up to 175 oC.
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