医用钛合金增材制造技术及其组织性能调控是金属医用材料领域研究的热点。高强度低模量β型多功能钛合金是一类结构与功能性兼备的新型医用金属材料，其强度与模量比值约为2%，显著高于传统的晶态金属材料；具有非线性弹性变形行为，在高强度条件下宽温域范围内具有超弹性和高阻尼性能等。课题组前期结果表明，纳米尺度相分解和晶体结构连续可逆变化的马氏体相变是产生该类合金特殊性能的根源。本课题拟采用3D打印技术制备高强度低模量β型钛合金，结合理论计算和实验，研究电子束增材制造过程中的温度场特性，阐明超常凝固条件及复杂热历史下Ti2448合金元素迁移规律、相分解机制及其对马氏体连续相变的影响，建立电子束工艺参数-相分解-连续相变-力学性能之间关联，揭示时效处理后处理对电子束增材制备构件的HCP相均匀形核及生长影响机制，为通过调整增材制造工艺参数优化高强度低模量β型钛合金组织和性能提供理论依据。

The investigation on the microstructure and mechanical properties of additive manufactured biomedical titanium alloys has recently received extensive attentions and becomes a hot topic for the development of biomedical metallic materials. Titanium alloy with high strength and low modulus possess high strength-to-modulus ratio (~2%), nonlinear elastic deformation, superelasticity and high damping across a wide temperature range (from below 4.2K to 573K). Our previous investigations of a Ti-Nb based alloy have found that nanoscale elastically confined martensitic transformation (MT) mechanism because of a nanoscale Nb modulation created by spinodal decomposition is the origin of these unprecedented properties. In this project, the titanium alloy with high strength and low modulus will be fabricated by electron beam melting (EBM) technique. The temperature distribution in powder bed during EBM process will be described using finite element calculations. The alloy elements migration, phase separation and its effect on MT under unique solidification condition and complex heating history during EBM will be clarified. The relation between processing parameters and phase separation will be established and their influences on martensitic transformation and mechanical properties will be elucidated. The effect of post aging treatment on the HCP phase precipitation in EBM product will be revealed. Above results will provide the theoretical guidance for optimizing the microstructure and mechanical properties of EBM titanium alloy products with high strength and low modulus through adjusting EBM processing parameters.