合金元素对β-γTiAl合金热处理组织的影响

Effects of Alloying Element on the Heat-Treated Microstructure Based on β/γ TiAl

以Ti-Al-M三元合金(M为V、Mo强β相稳定元素)为对象,研究了合金元素V、Mo、Al对其铸态组织以及不同热处理条件下显微组织的影响。增加β相稳定元素可以将β相保留在室温,但是仅通过降低Al含量而获得β相凝固合金(Ti-38Al),铸态组织中不含β/B2相。Al含量较高时,添加β相稳定元素仍不能消除枝晶偏析。在合金淬火组织中,增加V、Mo元素或者降低Al元素含量可以发生马氏体转变。在双步热处理过程中,由于1320℃淬火的过饱和作用,Ti-Al-Mo合金经过1200℃随炉冷却后,组织内将会同时析出β相和γ相,形成β+γ的混合组织。

Based on Ti-Al-M (M represents β phase stabilizing elements,such as V and Mo)alloys,the effects of V,Mo and Al elements on as-cast microstructure as well as the microstructure of different heat treatment processing were studied.Results show that with the content of β phase stabilizing elements increasing,β phase can be preserved to room temperature.However,the β phase solidification microstructure produced just by decreasing Al content in TiAl alloys does not contain β phase.The microsegregation cannot be removed through adding β phase stabilizing elements when the Al content of alloys is higher.The martensite mode can be observed in the microstructure subjected to water quenching,with increasing the content of V,Mo elements or decreasing the content of Al.During two-step heat treatment process,Ti-Al-Mo alloys subjected to water quenching from 1320 ℃ are in supersaturation state;so after furnace cooling from 1200 ℃,β andγ precipitate from the microstructure to form a mixed microstructure of β+γ.