机械合金化制备Ti-Al-Si纳米金属间化合物

Formation of Nanocrystalline Intermetallic Compounds for Ti-Al-Si System by Mechanical Alloying

4种成分的Ti-Al-Si颗粒T3，T4，T5和T6通过球磨获得非晶．这些非晶在退火时的结构变化分为3个阶段：（1）球磨非晶的部分晶化并产生Ti5Si3；（2）其余非晶的完全晶化并依赖于颗粒中Ti和Al的组成产生钛铝金属间化合物，（3）粉末中各相的晶粒长大．晶化反应依粉末成分产生Ti3Al，TiAl和Al3Ti.Ti5Si3是晶化反应的唯一硅化物.低于800℃退火可获得纳米晶。

Amorphous phase was obtained by mechanical alloying of Ti-Al-Sipowders with four different composition. The structure evolution of the as-milled amor-phous phase during the annealing treatment is classified into three stages: the first ispartial crystallization of amorphous phase producing Ti5Si3 phase; the second is crystalliza-tion of the rest amorphous phase producing the corresponding titanium aluminides accord-ing to the relative amount of Ti and Al in the elemental mixture; and the last one isgrain growth of all the phase in powders. The crystallization result in formation of Ti3Al,TiAl and Al3Ti according the powder composition. Ti5Si3 is the only silicide produced bycrystallization reaction. The annealing treatment (less than 8OO℃ for A3, A4 and A5, and750℃ for A6) shows that the grain size of all the phases fall in nanometer range.