((1. 北京科技大學(xué) 材料科學(xué)與工程學(xué)院，北京 100083；2. 北京鋼鐵研究總院 高溫材料研究所，北京 100081))
摘 要: 采用SEM等方法觀察經(jīng)β相區(qū)溫度鍛造的Ti-22Al-25Nb合金在β相轉(zhuǎn)變點(diǎn)以下不同熱處理過程中的微觀組織轉(zhuǎn)變，測(cè)試所得組織狀態(tài)下的合金拉伸性能。對(duì)該合金的微觀組織轉(zhuǎn)變規(guī)律以及與拉伸性能的關(guān)系和機(jī)理進(jìn)行分析。結(jié)果表明，在固溶處理過程中，組織中原有的α2相顆粒和O相板條因溶解而減少，B2相基體含量相應(yīng)增大；固溶處理溫度升高可加劇各相含量的變化趨勢(shì)，并在這一過程中伴隨著B2相的再結(jié)晶且α2相和O相的存在對(duì)B2相的再結(jié)晶有限制作用；在時(shí)效過程中，O相以細(xì)小二次板條形式從B2相基體中析出，或在殘留的α2相顆粒周邊以塊狀形式生成。該合金經(jīng)不同固溶＋時(shí)效處理后均具有良好的室溫及高溫拉伸性能；且因固溶溫度升高造成細(xì)小O相二次板條含量增多而使合金呈強(qiáng)度升高、塑性下降的趨勢(shì)，其中以1 000 ℃固溶＋800 ℃時(shí)效處理的狀態(tài)具有強(qiáng)度和塑性的最佳匹配。
關(guān)鍵字: Ti-22Al-25Nb合金；組織轉(zhuǎn)變；固溶溫度；拉伸性能
（(1. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China;2. High Temperature Material Research Institute, Central Iron and Steel Research Institute, Beijing 100081, China)）
Abstract:Microstructure transition of Ti-22Al-25Nb intermetallic alloy forged in β-phase zone during different heat treatments were observed by SEM, and the tensile properties were also tested. The law of microstructure transition and the relationship between the microstructure and the properties were analyzed. The results show that during the solution process, the content of B2 matrix increases while those of the α2 phase and the O phase decrease for dissolution; this trend is aggravated with the increase of the solution temperature, going along with the recrystallization of B2 phase. The recrystallization of B2 phase is limited by the existence of α2 phase and O phase. At the age process, the slender O laths precipitate from the B2 matrix or around the retained α2 particles in massive form. The alloy has good tensile properties at room or elevated temperature after different heat treatments. With the increase of the solution temperature, the slender secondary O laths increase, which makes the strength increased and the ductility decreased. After 1 000 ℃ solution +800 ℃ aging treatment, the alloy has the best combinations of the strength and ductility.
Key words: Ti-22Al-25Nb intermetallic alloy; microstructure transition; solution temperature; mechanical property
