Replacement with Each Other of Ti and Zr in the Intermetallics of Al-(Si-) Ti-Zr Alloys

The structures and compositions of Ti and Zr rich phases in ternary Al Ti Zr and quaternary Al Si Ti Zr systems were investigated by energy dispersive spectroscopy and X-ray diffraction. The additions of Ti and Zr were changed. It was found that Ti and Zr can replace each other in the Ti and Zr rich phases of Al (Si)Ti Zr alloys. Compositions of the phases have been measured as a function of Ti and Zr additions. The content of Ti (Zr) in the phases increases with its addition in the alloys. Besides, the increase of Ti content can result in a decrease of lattice parameters. Microhardness of the phases in Al-18Si xTi yZr alloys changes with composition evolution. Moreover, the microhardness is higher than that of the intermetallics of ternary Al Si Ti and Al Si Zr alloys, due to the distortion of crystal structure caused by the replacement of Ti and Zr.