片层Ti-6Al-4V合金的界面结构及性能

郑士建 刘正 郑晓东 马英杰

摘要 界面工程是提升工程合金强度和塑性等力学性能的重要途径。双相片层Ti-6Al-4V合金作为典型的工程合金，其原子尺度界面结构对材料变形行为和强塑性的调控作用尚不清晰。本文综述了传统片层Ti-6Al-4V合金中α/β界面和增材制造法制备的片层Ti-6Al-4V合金中α/界面层/β和α′/β界面对强塑性的影响。因为α/β界面两侧存在特定的取向关系，所以对不同滑移方向位错运动的阻碍作用具有各向异性，同时其原子尺度台阶状的界面结构又促进了孪晶在界面处的形核。α/界面层/β界面结构因为界面层的存在，对位错运动具有更强的阻碍作用，并且在较低应变下产生形变孪晶，促进孪生变形;α′/β界面结构因为α′和β两相显著的变形不协调导致界面应力集中， 在α′/β界面处易形成微裂纹。这些不同的界面结构导致材料强塑性的差异。通过系统论述Ti-6Al-4V合金不同界面结构对材料变形行为及强塑性的影响，为合理设计界面结构实现双相Ti-6Al-4V合金强塑性的提升提供思路。

关 键 词 界面;片层Ti-6Al-4V合金;强塑性;透射电子显微学

中图分类号 TG135.1     文献标志码 A

Abstract Interface engineering is an important way to improve the mechanical properties such as strength and plasticity of engineering alloys. The dual-phase lamellar Ti-6Al-4V alloy is a typical engineering alloy， and its atomic-scale interface structure has an unclear control effect on material deformation behavior and strength and plasticity. This article reviews the effects of α/β interface in traditional lamellar Ti-6Al-4V alloy and α/interface layer/β and α′/β interface in lamellar Ti-6Al-4V alloy prepared by additive manufacturing on strength and plasticity. Because of the specific orientation relationship on both sides of the α/β interface， the hindering effect on the movement of dislocations in different slip directions is anisotropic， and its atomic-scale step interface structure promotes the nucleation of twins at the interface. The α/interface layer/β interface structure has a stronger hindering effect on the movement of dislocations due to the existence of the interface layer， and produces deformation twins under lower strain， which promotes twin deformation; The α′/β interface structure is due to the significant inconsistent deformation of the α′ and β phases， which causes the interface stress to concentrate， and microcracks are prone to form at the α′/β interface. These different interface structures lead to differences in material strength and plasticity. By systematically discussing the effects of different interface structures of Ti-6Al-4V alloy on the deformation behavior and strength and plasticity of materials， it provides ideas for the rational design of the interface structure to achieve the improvement of the dual-phase Ti-6Al-4V alloy strength and plasticity.

Key words interface; lamellar Ti-6Al-4V alloy; strength and plasticity; transmission electron microscopy

0 引言

金屬材料在工业应用中有着不可替代的作用。快速发展的航空航天等领域对金属材料的性能要求越来越高，而金属材料强度-塑性倒置关系一直是金属材料领域的热点和难点问题，例如强度的提升通常会伴随一定塑性的损失。国内外大量研究表明[1-4]，界面工程可以有效地提升金属结构材料的综合力学性能。……