Interfacial Science of Nano-lamellar Materials

研究了由α_2Ti_3Al相和γ-TiAl相组成的纳米片层材料的力学性能。这种材料中含有大量的α_2/γ界面，阻碍了位错的运动，提高了材料的强度。纳米片层材料的弹性极限对片层厚度λ不敏感，但无失配位错的界面提供了较高的弹性极限。纳米片层材料的加工硬化率与λ成反比，失配位错的引入增加了加工硬化率。高温下α_2/γ界面的消失会导致纳米片层材料的退化。加入β_0相形成元素后，α_2片层溶解，形成β_0析出物条带。α_2片层消失后，析出带具有较高的蠕变强度。

The present research studied mechanical properties of nano-lamellar materials consisting of α_2Ti_3Al phase and γTiAl phase. This type of materials contains a large number of α_2/γ interfaces, which act as obstacles to dislocation motion and improve strength of such materials. Elastic limit of nano-lamellar materials is insensitive to lamellar thickness λ, but the interfaces without misfit dislocation provide a higher elastic limit. Work-hardening rate of nano-lamellar materials is inversely proportional to λ, and the coefficient is increased by the introduction of misfit dislocations. Disappearance of α_2/γ interfaces during high temperature exposure causes degradation of nano-lamellar materials. Bands of β_0 precipitates are formed after dissolution of α_2 lamellae when a β_0 phase forming element is added. The precipitation bands give high creep strength after the disappearance of α_2 lamellar.