La对Ti-44Al-6Nb合金组织及性能的影响Effect of La on microstructure and mechanical property of Ti-44Al-6Nb alloy

采用La对Ti-44Al-6Nb进行合金化处理，La元素的含量分别为0、0.3%、0.6%、0.9%和1.2%(摩尔分数)。对熔炼后的钮扣锭的表面质量、宏观组织、微观组织、压缩性能和断口形貌进行观察和分析。结果表明：La对表面质量影响较大，含量较高时，表面有起皮现象，表面质量被恶化；La元素的添加能够细化晶粒，但是含量不同，细化效果有较大区别，含量为0.3%和0.9%时细化效果较好，晶粒最小可达到0.1 mm。压缩试验表明：La添加后强度和塑性均有较大程度的提高，压缩率最大可提高100%左右；晶粒细化和晶界强化是提高性能的主要原因。

Different contents (0, 0.3%, 0.6%, 0.9%, 1.2%, mole fraction) of La were added into Ti-44Al-6Nb alloys to prepare ingots. The surface quality, macrostructure, microstructure, compressive properties and fracture surface of the ingots were studied. The results show that La has bad influence on the surface quality, especially when the content is higher. La can refine the grains of the ingots, whereas, the refining effect is different for different La contents, it is better when the contents are 0.3% and 0.5%, and the smallest grain can reach 0.1 mm. The compressive testing results show that La can improve the strength and ductility, the compression ratio can be improved by about 100%, which is owing to grain refining and boundary and grain-boundary strengthening.

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