Research On Microstructure And Properties Of β-γ Type Tial Alloys

In this experiment,the typicalβ-γtype titanium alloy Ti-44Al-4Nb-1Mo-0.1B is used as the basic component（hereinafter referred to as the matrix alloy）,in which theβ-phase stable element Cr,V,Nb and rare earth element Y are added to the alloy.The effects of alloying elements on microstructure,high temperature oxidation resistance and hardness of Ti-44Al-4Nb-1Mo-0.1B alloy were investigated.The experimental results are as follows:（1）The microstructure of all alloys is composed of lamellar clusters and B₂ phases.The addition ofβ-phase stable elements makes the lamellar clusters of the alloy finer,the grain size of the alloy containing 3Cr is the smallest,and the grain size of the unalloyed matrix alloy is the largest;（2）After homogenization treatment,the B₂ phase between the lamellae decomposes,the alloy has different microstructure,the unalloyed matrix alloy is near dual structure,the 1Cr alloy is full lamellar structure,and the 1V alloy is dual structure.The binary structure of 0.1Y alloy and the near dual structure of 6Nb indicate that the Cr alloy elements can decrease the Tαtemperature of the matrix alloy.For this alloy,the Nb element has no great effect on the Tαtemperature,and Y,V element increases the Tαtemperature relatively;（3）Among the alloying elements,Nb and Y had obvious effect on the high temperature oxidation resistance of the alloy,and Cr,V decreased the high temperature oxidation resistance of the alloy.The oxidation resistance of 8Nb alloy is the strongest at high temperature,the oxidation resistance of 0.3Y alloy is the second,the oxidation resistance of 3V alloy is the worst,the hardness of 3Cr alloy is the highest and the hardness of0.3Y alloy is the lowest;（4）Among the alloys studied,the addition of Cr,V worsens the high temperature oxidation resistance of the matrix alloy,Y and Nb improves the high temperature oxidation resistance of the alloy,and combines the high temperature oxidation resistance and hardness test.The alloys after alloying with Y and Nb have continued research value.