Effect of silicon and titanium on the microstructure and mechanical properties of ZA12 alloy

In this paper, the effects of Si alloying and Si-Ti complex alloying on the microstructure and mechanical properties of ZA12 alloy were studied by optical microscopy, scanning electron microscopy/energy dispersive spectrometry, Vickers microhardness tests, and impact tests. The results showed that when 0.1-0.3 wt% Si was added to ZA12 alloy in the form of an Al-20Si master alloy, a fine silicon phase was formed in the alloy. Although the hardness of the alloy greatly increased, its impact toughness decreased. When 0.8 wt% Si was added into ZA12 alloy in the form of an Al-12.6Si master alloy, the alloy hardness was higher than when 0.1 wt% Si was added in the form of Al-20Si master alloy. After adding 0.8 wt% Si + 0.3 wt% Ti into ZA12 alloy, the hardness and impact toughness reached 138 HV and 23.8 J.cm(-2,) respectively, which were 13.1% and 28% higher than those of non-alloyed ZA12. Complex alloying using Si and Ti improved the comprehensive mechanical properties of ZA12, which was attributed to the complex strengthening effect of fine TiSi2 particles and relatively small silicon particles in the alloy.

Automated summary

The addition of Si alloy and Si-Ti complex alloying can increase the hardness of ZA12 alloy, but may decrease its impact toughness. Complex alloying using Si and Ti can simultaneously improve the hardness and impact toughness of the alloy, enhancing the comprehensive mechanical properties.