真空吸铸TiAl基合金组织研究

Structure of TiAl Based Alloy by Suction Casting

利用金属型真空吸铸技术获得了TiAl基合金薄板件,并研究了该铸件的铸态组织以及合金元素对其组织的影响。实验结果表明:由于金属型的强制冷却作用,金属型真空吸铸的Ti-47Al合金薄板铸件铸态组织细小,平均晶粒尺寸在60μm左右;W元素的添加有利于B2相的形成,从而细化组织,其机理是B2相阻碍了α晶粒长大;Si元素添加生成的Ti5Si3相,主要分布在晶界处,形成的Ti5Si3第二相质点会阻碍TiAl基合金凝固过程中组织的长大,有利于细化TiAl基合金组织。

The TiA1 based alloy sheets were achieved by the permanent mould suction casting. This as-cast structures and the effect of alloy elements on structures were studied. The results indicated that because of force cooling, the as-cast structures of TiA1 based alloy sheet by permanent suction casting are fine, and the average grain size is 60 i.Lm. The B2 phase counteracts α phase grow, and the adding of W element benefits to form B2 phase. Therefore, the addition of W element can refine the grain size of TiA1 based alloy structure. The Ti5Si3 phase formed by adding of Si element is mainly situated at the grain boundary. The particle of the TisSi3 phase counteracts the structure grow on solidification process, so the adding of Si element can refine the grain size of TiA1 based alloy struc- ture.