Effects of TiC additions on as cast and heat treated microstructures and mechanical properties of ZA84 magnesium alloy

Abstract

The effects of TiC additions on the as cast and heat treated microstructures and mechanical properties of ZA84 Mg alloy are investigated. The results indicate that, after adding 0·5 wt-%TiC to ZA84 alloy, the as cast microstructure of the alloy is refined. At the same time, the distribution of second phases in the alloy becomes relatively uniform and the quasi-continuous networked second phases in the alloy become discontinuous. As a result, the as cast tensile properties of the alloy are improved. In addition, after solutionisation at 345°C, parts of the Mg₃₂(Al,Zn)₄₉ phases in the ZA84 alloy without TiC modification still exhibit quasi-continuous distribution. The Mg₃₂(Al,Zn)₄₉ phases in the ZA84 alloy treated with 0·5 wt-%TiC change to disconnected particles with an angular morphology and gradually spheroidise. Under the optimum heat treated conditions, the ZA84 alloy treated with 0·5 wt-%TiC exhibits higher heat treated tensile properties than the ZA84 alloy without TiC modification.