Experimental Study on Preparation of Cr-containing Ti-Al Based Alloys by Aluminothermic Reduction-remelting of Waste SCR Ti-based Denitration Catalyst

Ti-Al based alloys were prepared for the first time by aluminothermic reduction-remelting method using scrap selective catalytic reduction（SCR） catalyst as raw material.The effects of Cr on the microstructure,phase compositions and properties of the alloys were also studied by adding different contents of Cr.X-ray diffraction（XRD） and energy dispersive spectroscopy（EDS） analysis show that the phases observed in the alloys without adding Cr element are mainly composed of Ti_0.8V_0.2Al₃,TiAl₂,Ti₃Al,TiAl,Ti₅Si₃,TiSi₂,CaAl₄O₇,Ca₂AlSiO_5.5 and so on.Adding Cr element can reduce the formation of Al-rich titanium aluminide compounds,and reduce the content of Ca-Al oxides.It can also form Ti_0.25Cr_0.08Al_0.67 phase,and increases the formation of Ti₃Al and TiAl phases.The phase evolution calculation by Pandat thermochemical software shows that the addition of Cr can significantly reduce the phase ratio of Al₃（Ti,V） and decrease a certain amount of（Ti,Cr）₅Si₃,and can increase the formation of TiAl phase.The hardness test results show that the hardness of the alloy increases with the increase of Cr content.This may be due to the uniform distribution of equiaxed TiAl-like phases and the decrease of（Ti,W）₅Si₃ phase.