Al元素对TiAl-6Nb合金铸态组织及硬度的影响

Effect of Al elements on microstructure and hardness of TiAl-6Nb alloys

本文利用真空非自耗电弧熔炼设备制备了Ti-(44-54)Al-6Nb合金锭,并对其铸态组织和硬度进行了系统地研究。结果表明,随着Al含量的不断增加,TiAl-6Nb三元合金的枝晶形态由四重对称演化为六重对称,其凝固初生相由β相向α相转变。且随着Al含量的增加,B2相的分布形态由枝晶内的网络状分布转变为枝晶边缘的富集。通过对TiAl-6Nb合金的硬度研究发现,随着Al含量的增加其硬度变化呈现先降低再增加再减少的变化趋势,这主要是由于不同的相含量和B2相的分布形态变化所致。

The solidification structures and hardness of Ti-（44-54）Al-6Nb alloys have been studied systematically, which was prepared by smelting and casting in the non-consumable electric arc melting process. It revealed that, the dendritic morphology transforms form a fourfold symmetry to a sixfold symmetry with the increasing of Al content. That is to say, the primary phase transforms form β phase to α phase. The distributional morphology of B2 phase transforms form network state in a dendritic crystal to enrichment in a dendritic edge wiht the increasing of A1 content. By study on the hardness of TiAl-6Nb alloy, the results show that the change of hardness value is not monotonically increasing or decreasing with the increasing of A1 content. It is mainly due to the different phase content and the distributional mophology of B2 phase.