Effect Of Hf, Si Alloying And Heat Treatment On The Microstructure Refinement Of Ti-Al Alloy

Cast Ti-46 Al alloy has coarse columnar crystals which is brittle, and has poor ductility at room temperature, in order to refine the microstructure of Ti Al alloys,the paper added element Hf, Si to achieve refinement. Double heat treatment makes it uniform and fine layers.We Discussed Ti Al ternary alloy solidification organization characteristics,contains Hf、Si. Hf makes columnar grain refinement, Ti Al alloy containing Hf exists the dots and strips of B2 phase. B2 phase is the cause of promoting the formation of nuclei. When adding amount is more than 5% Hf. Grain refinement, dot B2 phase, obviously promote a large number of crystal nucleus formation, Hf partial poly dendrite. In the research of Ti Al containing Si ternary alloy, with refinement effect is found Ti5Si3 phase, Ti5Si3 inhibiting alpha grain growth, promoting the isometric transformation.At the same timethe four containing Hf, Si yuan Ti Al alloy solidification organization characteristics was studied. With Hf and Si is creasing gradually in the columnar crystal bulky columnar crystal to fine dendrite final transition to appear That can improve mechanical properties of a large number of cubic. The quaternary alloy with numerous B2 and Ti5Si3 facies, microtek distribution between Hf partial poly shifting from the dendrite dry to interdendritic, have the effect of stable B2 and Ti5Si3 facies.Focusing on Ti-46Al-(3,5,7)Hf, and selection of Ti-46Al-7Hf as the research object, the heat treatment to discuss different solid solution process, the influence of different tempering processes on the final tempering organization, in order to obtain the best pair of warm treatment. Experimental research shows that: aft er 1380 ℃,1h, quenching process again 1280℃, 3 h tempering process, That can get tiny layer.Use of the best heat treatment were applied to Hf, Si quaternary alloy, found that the Hf in contrast to the Si on the influence of heat treatment process. The addition of Si improved the phase transition point, hindered the process of heat treatment.