片层Ti-6Al-4V合金的界面结构及性能

Interface structure and properties of lamellar Ti-6Al-4V alloy

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。

Interface engineering is an important way to improve the mechanical properties such as strength and plastici⁃ty of engineering alloys.The dual-phase lamellar Ti-6Al-4V alloy is a typical engineering alloy,and its atomic-scale inter⁃face structure has an unclear control effect on material deformation behavior and strength and plasticity.This article re⁃views the effects ofα/βinterface in traditional lamellar Ti-6Al-4V alloy andα/interface layer/βandα′/βinterface in la⁃mellar Ti-6Al-4V alloy prepared by additive manufacturing on strength and plasticity.Because of the specific orientation relationship on both sides of theα/βinterface,the hindering effect on the movement of dislocations in different slip direc⁃tions is anisotropic,and its atomic-scale step interface structure promotes the nucleation of twins at the interface.Theα/interface layer/βinterface 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;Theα′/βin⁃terface structure is due to the significant inconsistent deformation of theα′andβphases,which causes the interface stress to concentrate,and microcracks are prone to form at theα′/βinterface.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 de⁃sign of the interface structure to achieve the improvement of the dual-phase Ti-6Al-4V alloy strength and plasticity.