La對Ti-44Al-6Nb合金組織及性能的影響Effect of La on microstructure and mechanical property of Ti-44Al-6Nb alloy

采用La對Ti-44Al-6Nb進行合金化處理，La元素的含量分別為0、0.3%、0.6%、0.9%和1.2%(摩爾分數(shù))。對熔煉后的鈕扣錠的表面質(zhì)量、宏觀組織、微觀組織、壓縮性能和斷口形貌進行觀察和分析。結(jié)果表明：La對表面質(zhì)量影響較大，含量較高時，表面有起皮現(xiàn)象，表面質(zhì)量被惡化；La元素的添加能夠細化晶粒，但是含量不同，細化效果有較大區(qū)別，含量為0.3%和0.9%時細化效果較好，晶粒最小可達到0.1 mm。壓縮試驗表明：La添加后強度和塑性均有較大程度的提高，壓縮率最大可提高100%左右；晶粒細化和晶界強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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