Experimental Study of Vacuum Electromagnetic Levitation Refining of TiAl Intermetallic Alloy

Refining of crude Ti Al based alloy which was obtained through aluminothermic reduction of acid-soluble titanium slag in Panzhihua was carried out using vacuum electromagnetic levitation melting furnace. Phase composition,distribution of alloy elements in micro area,microstructure and impurities content of the alloy before and after refining were studied in present study. It is found that when the refining parameters of melting current,holding time and cooling rate were respectively 60 A,5 min and 4 A/min,the lamellar structures,amount of cracks and grain size of the alloy after refining decreased. Si and Fe presented in the phases of TiAl and TiAl₂ etc. by substituting Al element to form substitutional solid solution phases,and eventually formed the phases of Fe₂AlTi,Si₂Ti,Al₂FeSi,AlFe and FeTiSi etc.,close to the double phase structure of Ti-Al binary alloy. The inclusions content in the alloy reduced by 45% and inclusions with size more than 5 μm were removed by refining.