等径弯角挤压制备超细晶亚稳Ti-25at.%Nb合金研究

Study of Ultra-Fine Grained Metastable Ti-25 at. % Nb Alloy Fabricated by Equal Channel Angular Pressing

在中温550℃对Ti-25 at.%Nb合金进行ECAP挤压4道次处理后,合金的微观组织为拉长晶粒,不能得到细小的等轴晶粒。挤压温度降低至400℃,ECAP挤压后合金的晶粒可得到明显细化,其中,经过2道次ECAP挤压后,微观组织以拉长态的晶粒为主,局部区域出现晶粒尺寸约为500 nm的细小等轴晶粒;在400℃经过ECAP挤压4道次,组织进一步细化为200-300 nm等轴细小晶粒。

The paper studied microstructure of Ti-25 at. % Nb alloy. The results showed that grain structure was elongated but without obtaining equiaxed UFG after 4 passes ECAP at 550℃; grain refinement became obvious as process temperature decreased to 400℃,among which,most grains were elongated,and some equiaxed UFG were observed with a grain size of500 nm after two passes ECAP; equiaxed UFG were obtained after 4 passes ECAP at 400 ℃ with a grain size of 200 - 300 nm.