高强高韧钛合金的强韧化机制及成分优化基础研究

先进武器装备的快速发展对高强高韧钛合金的强韧性匹配提出了更高要求。目前，高强高韧钛合金的成分设计多基于半经验规律，亟需发展建立在强韧化机制基础上的成分优化设计方法，对合金进行精准的成分优化设计。高强高韧钛合金通过alpha沉淀相强化beta相基体。合金的强韧性及其机制与alpha及beta相的基本物性参数如晶格常数、弹性模量、层错能、位错滑移临界剪切应力等的错配密切相关。然而，合金的主导强韧化机制及关键物性参数仍不明确。本项目拟采用第一原理方法，计算上述物性参数，考察不同强韧化机制对合金强韧性的贡献，明确合金的主导强韧化机制，确定基于关键物性参数的成分设计指标；揭示合金成分影响上述参数进而影响强韧性的规律。基于上述研究，提出Ti-Al-Mo-V-Cr基高强高韧钛合金的成分优化方案，并进行实验验证。本项目可望为发展我国自主知识产权的高强高韧钛合金提供理论基础。

The rapid development of advanced military hardware urges improvement in strength-toughness trade-off of high strength high toughness titanium alloys. Up to date, the composition design of high strength high toughness titanium alloys is mostly based on some semi-empirical rules. Mechanism based alloy design approach is highly demanded for the precise composition optimization so as to get the best strength-toughness trade-off. In general, high strength high toughness titanium alloys gain their high strength through alpha precipitation strengthening of the beta matrix. For this type of alloys, the strength and toughness and their underlying mechanisms are highly related to the mismatch of fundamental parameters such as lattice constants, elastic moduli, stacking fault energies, and critical resolved shear stresses of the alpha and beta phases. Unfortunately, the dominant mechanisms for the strengthening and toughening and the key parameters are still to be explored. In this project, we propose to calculate these parameters by using a first-principles method, investigate the contributions of various mechanisms to the strength and toughness so as to clarify the dominant mechanisms, determine the key-parameter based composition design indictors, and elucidate the regularity of the influence of the composition on the key parameters and subsequently the strength and toughness. With which, we will try to optimize the composition of Ti-Al-Mo-V-Cr based high strength high toughness alloy and verify it experimentally. The outcomes of this project will hopefully provide some theoretical basis for the development of high strength high toughness titanium alloy with independent intellectual property rights of our country.