高纯度Al_3Ti粉末的制备及细化

Fabrication of High Purity Al_3Ti Powder and Its Refinement

以Ti、Al粉末为原料,对比研究了利用直接烧结法与球磨和烧结结合法制备较纯Al3Ti粉末的Ti、Al摩尔比和温度,并探讨了将该金属间化合物细化至纳米级粉末的可能性。结果表明,球磨和烧结结合法可降低Al3Ti的形成温度,得到更加细小的微米级别的Al3Ti粉末。球磨过程虽未直接形成Al3Ti相,但粉料的细化和良好的结合、形核相的急剧细化、大量新鲜表面的存在、组元活性的增强等促使了反应温度和颗粒大小的降低。球磨烧结时Ti、Al的摩尔比为理论摩尔比1.0∶3.0,大大小于直接烧结法所需的摩尔比1.0∶2.5,且可避免直接烧结反应形成Al3Ti颗粒时内部有可能存在的"Ti核"。利用机械球磨对Al3Ti相的细化表明,可利用常用的设备,在适当的气氛保护下就可制备得到纳米级的金属间化合物。

Effects of direct sintering and ball milling combined with sintering on Ti/Al ratio and forming temperature in fabricating high purity Al3Ti powder were analyzed with commercial Ti and Al powder,and possibility of refining grain size to nano-meter Al3Ti powder was approached. The results show that the forming temperature of Al3Ti particle can be decreased and very fine micron Al3Ti powder can be obtained by ball milling combining with sintering method,which is attributed to the decrease of reactive temperature and particle size resulting from refinement and desirable bonding of Al and Ti powder in processing of ball milling leading to the sharp refinement of nucleation phase and exposure of amounts of fresh surface as well as increasing in composition activation. The molar ratio of Ti/Al is equal to the theoretic values of 1∶3 in ball milling combining with sintering method,which is less than 1∶2.5 in direct sintering method. In addition,the absence of Ti nuclei in formed Al3Ti particles in ball milling combining with sintering can be observed,superior to that in direct sintering. The refinement of Al3Ti particles by mechanical ball milling reveals that the nano-Al3Ti particles can be successfully prepared by common equipment at proper atmosphere .