EFFECT OF Al-Ti-B ON MAGNESIUM ALLOY MICRO-ALLOYED WITH Ca

Effect of Al-Ti-B master alloy on the microstructure and mechanical properties was investigated in AZ31 magnesium alloys micro-alloyed with Ca. During the casting process, electromagnetic field was also introduced. The results suggest that the micro addition of Ca to magnesium alloy retards the oxidation rate during melting process, improves casting qualities of magnesium alloy ingots. The grain size of AZ31 magnesium alloy has been effectively reduced by optimum addition of 1 wt.% (designed composition) Al-Ti-B master alloy. In this process, the addition level of Ti is the key factor to affect grain size of magnesium alloy, in which two grain refinement mechanisms are built by both TiB2 and residual Ti. Moreover, the electromagnetic field leads to uniform distribution of temperature field and solute field in the molten pool, increases casting qualities and refines grain size further.