氧含量过高导致的脆性问题是制约粉末冶金Ti-6Al-4V合金应用的关键。为了解决这个问题，目前大多数的研究集中在使用低氧含量的预合金粉末或在合金制备过程中引入脱氧剂来降低氧含量，原材料和工艺成本较高，限制了Ti-6Al-4V的工业化应用。本项目采用元素粉末法制备低成本的Ti-6Al-4V合金，针对烧结后合金中高氧含量和细长片层组织的问题，提出了通过微观结构调控来提高钛合金塑性的热处理方法。利用氧元素在α和β相中的固溶度差异，巧妙地将合金中有害的氧元素转变为部分有益的性能调控元素，通过热处理使氧元素重新分配形成高强度的富氧相和高塑性的贫氧相，在二者的协同作用下提高合金的塑性；并且通过热处理改变合金中初生α相的形态，降低α相的长径比来提高合金的塑性。深入研究这种微观结构调控技术对高氧Ti-6Al-4V合金塑性变形影响的机理，为该技术在其他钛合金体系的推广提供理论基础。

The brittleness caused by high oxygen content is a crucial problem which limits the applications of Ti-6Al-4V alloy. To solve this problem, most studies focused on the utilization of spherical prealloyed titanium powders with low oxygen content or the addition of deoxidizers to reduce oxygen content in the preparing process. However, the high cost of raw powders and preparation limits the industrial applications of Ti-6Al-4V alloy. In this research, elemental powder method is applied to fabricate low-cost Ti-6Al-4V alloy. A new heat treatment method is proposed to improve the plasticity of Ti-6Al-4V alloy with high oxygen content and lamellar microstructure. The difference of oxygen solubility between α and β phases is used to transform the harmful oxygen element into beneficial element to control the properties of the alloy. As a result, the oxygen atoms are redistributed by heat treatment to form high-strength oxygen-rich part and high-plasticity oxygen-depleted part, so that the plasticity of the alloy is improved under the interactions of the two parts. Additionally, the morphology of primary α phase is changed by heat treatment, and the plasticity of Ti-6Al-4V alloy is improved due to the reduction of the aspect ratio of α phase. To study the mechanism of plasticity improvement, the heat treatment method based on oxygen redistribution and changing the morphology of α phase is furtherly investigated. The research will provide theoretical basis for applying the developed heat treatment method on other titanium alloy systems.