电铝热还原法制备TiAl合金理论及试验研究

Theoretical and Experimental Research on Preparation of Ti-Al Alloy by Electric Aluminothermic Reduction

以钛白粉为原料,采用电铝热还原的方法一步合成制备Ti Al合金。研究了不同温度和不同配铝量对渣—金分离,渣系的物相,合金组织、成分和物相的影响规律。通过理论分析可以看出,焙烧温度提高,渣的黏度降低,有利于实现渣金分离,从试验研究可以看出,温度为1 550℃时渣金分离效果较好;配铝量对还原渣和合金的成分有较大影响,配铝量不足,渣中有较多的低价钛氧化物存在,导致渣的熔点升高和黏度增大,Al/Ti O2>0.7时,渣—金分离较好;配铝量增加提高了合金收率及钛收率,且使钛铝合金中铝含量增加及物相发生转变,Al/Ti O2=0.7,合金中的主要物相Ti Al和Ti3Al,Al/Ti O2=0.9时,主要物相为Ti Al和Ti Al3。通过XRD、SEM和能谱分析可以看出,合金中夹杂的渣的主要物相为Ca Al4O7。

Ti-Al alloy was prepared using electric aluminothermic reduction method with titanium white as raw materials.The influence of temperature and aluminum addition on the alloy-slag separation,phase of slag,microstructure,composition and phase of alloy were researched.Through theoretical analysis it shows that the elevated roasting temperature can lower the viscosity of slag in favor of the alloy-slag separation.A better separation of alloy and slag can be obtained at 1 550 ℃ according to the experiments.Addition amount of aluminium has significant influence on the compositions of alloy and slag.The melting point and viscosity of slag increase with presence of massive low-valence titanium oxides in the slag caused by insufficient aluminium addition,and the slag-alloy separation is favorable with Al/TiO2〉0.7.Increasing the aluminum addition can enhance the yield rate of alloy and titanium.Meanwhile,the aluminium content in Ti-Al alloy increases and the alloy phases convert.The main phases of alloy are TiAl and Ti3Al as Al/TiO2= 0.7 while TiAl and TiAl3 as Al/TiO2= 0.9.SEM,XRD and EDS analysis show that the slag included in alloy exists as CaAl4O7.