Microstructure And Properties Of Ti-44Al-4Nb-1Mo Enhanced By Nano Y₂O₃ And Er₂O₃

TiAl alloy has high specific strength,creep resistance,oxidation resistance and corrosion resistance,is a kind of high temperature structural material very promising,promising to replace high temperature Ni alloy,high density in high temperature field is low but at the same time,due to poor performance of TiAl alloy at room temperature and intrinsic brittleness,severe restrictions its application in engineering.Therefore,this topic will add nano refiners to TiAl alloy,and try to improve the room temperature properties of the alloy,and promote its application and development.This paper chooses Ti-44Al-4Nb-1Mo alloy as the research materials,using optical microscopy,scanning electron microscopy,XRD test methods,to study the effect of nano Y₂O₃,Er₂O₃ on microstructures and properties of cast alloy and forged alloys,as well as the effect under different temperature heat treatment on the Ti-48Al-4Nb-1Mo organization,to improve its performance and suitable method organization.Experimental results show that: More B2 phase particles exist in the alloy after added with nano Y₂O₃,while the content of B2 phase in Er₂O₃ alloy is equivalent to that of matrix.Nano Y₂O₃ can reduce the phase transformation temperature and keep more B2 phases at room temperature.In the thermal mechanical process,Y₂O₃ and Er₂O₃ on morphology of alloy dynamic recrystallization is also affected,the network like Er₂O₃ will lead to dislocation pile up more,but at the same time,the dislocation is also very difficult to form around the peroxide particles,only a large number of lattice defects in the alloy,However,the granular distribution of Y₂O₃,can nail dislocations and hinder grain growth and granular oxides do not prevent dislocations from bypassing the region.The recrystallization of the alloy with nano Y₂O₃ is more sufficient,while the alloy with Er₂O₃ addition and the matrix alloy recrystallization are not very sufficient,and the residual lamellae retain a more consistent orientation.The room temperature plasticity of Y₂O₃ alloy increases greatly after Thermomechanical processing.Different heat treatment can promote the TiAl alloy to obtain different microstructure,thus affecting the mechanical properties of the alloy.In the process of heat treatment,the grain of the alloy will grow rapidly with the increase of temperature.The microstructure of TiAl alloy increases with the increase of temperature: the lamellar microstructure,the lamellar structure,and the coarse lamellar structure;.The lamellar structure of the alloy with Y₂O₃ alloy is obtained at 1270?,while the alloy of TNM alloy and the alloy with nano Er₂O₃ alloy are still not obtained at full temperature of 1300?.