摘要
Al-5Ti-1B合金是铝及铝合金的高效晶粒细化剂,可显著改善铝及铝合金的加工性能,提高铝材的质量,但Al-5Ti-1B合金对纯铝及铝合金的晶粒细化机制目前尚未研究清楚。本文分别采用Al-5Ti-1B,Al-10Ti,Al-4B合金和TiB2粉末对纯铝进行细化实验,通过比较TiAl3,TiB2和AlB2对铝晶粒的细化作用,利用光学显微镜、X射线衍射仪、扫描电镜和透射电子显微镜,研究了Al-5Ti-1B合金的有效形核相和晶粒细化机制。结果表明,TiAl3是铝晶粒的有效异质形核相,但Al-5Ti-1B合金中的TiAl3因在铝熔体中会熔化而不是铝晶粒的直接形核相。单独的AlB2和TiB2都不是铝晶粒的有效异质形核相,但TiB2通过表面包覆TiAl3后可成为铝晶粒的有效异质形核相。Al-5Ti-1B合金细化铝晶粒的机制为:TiAl3熔解于铝熔体中释放Ti原子,一部分Ti原子通过浓度起伏形成TiAl3,TiAl3再与铝熔体发生包晶转变生成α-Al晶粒直接起到晶粒细化作用。剩余Ti原子在TiB2表面偏聚形成TiAl3,TiAl3再与铝熔体发生包晶转变生成α-Al晶粒起到晶粒细化作用。
Al-5Ti-1 B master alloy was a high efficient grain refiner of pure aluminum and aluminum alloy, which could significantly improve the processing performance of pure aluminum and aluminum alloy and the quality of aluminum products. However, the grain refinement mechanism of A1-5Ti-1 B master alloy on the pure aluminum and aluminum alloy was not clear. In the present work, the pure A1 was refined by adding Al-5Ti-1 B, AI-10Ti, A1-4B master alloy and TiB2 powder, respectively. The effects of TiA13 , TiB2 and A1B2 phases on grain refinement of pure A1 were compared. The effective nucleation phase and grain refinement mechanism of A1-5Ti- 1 B master alloy were investigated by optical microscope, X-ray diffraction, scanning electron microscope and transmission electron mi- croscope. The results showed that the TiA13 was an effective nucleation phase, but the TiAI3 in AI-5Ti-IB master alloy could not be nu- cleation phase due to dissolving in aluminum melt. The A1B2 and TiB2 could not be nucleation phase alone. However, the TiB2 could become an effective nucleation core when the TiB2 was coated with TiA13. The grain refinement mechanism of A1-5Ti-1 B master alloy on pure A1 was as follows： some Ti atoms originating from TiA13 melting reacted with A1 melt to form TiAI3 phase as the nucleation core of grain. Remaining Ti atoms segregated on the TiB2 surface to form TiA13 phase as the nucleation core of grain.
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2013年第2期179-185,共7页
Chinese Journal of Rare Metals
基金
广东省科技厅产学研重大科技专项项目(2009A080205004)资助
