钛合金是航空航天制造业中用量最大的一种金属材料，其中又以Ti-6Al-4V (Ti64)应用最为广泛。由于钛合金切削加工困难，激光选区熔化(SLM)作为一种增材制造新工艺，受到广泛关注。SLM-Ti64的显微组织为alpha'马氏体相，具有强度高、塑性差的特点。SLM-Ti64塑性差有两个原因。第一，alpha'相不易塑性变形。第二，材料中的残余beta相导致应力集中。在本项目中，我们将首先通过改变材料中的Al元素含量来调控alpha'相各滑移系的临界剪切应力(CRSS)，提升其塑性变形能力。接下来，通过同步辐射原位热处理实验来调控残余beta相的体积分数、尺寸和晶格常数。最后，借助同步辐射原位拉伸实验获得材料的力学性能，根据晶格应变、峰宽等信息理解材料的微观变形机制。根据这些研究结果，开发具有高塑性的新型SLM钛合金。

Titanium (Ti) alloys are the most widely used metals in aerospace manufacturing industry. Ti-6Al-4V (Ti64) is the most common Ti alloy. Because of the difficulty of material processing, selective laser melting (SLM), as a noval additive manufacturing process, has received strong attention. SLM-Ti64 has the alpha' martensite microstructure, which leads to high strength but poor ductility. The poor ductility can be attributed to two reasons. First, alpha' is difficult to make plastic deformation. Second, small amount of remnant beta phase often causes stress concentration. In this project, we will first change the concentration of Al in order to control the critical resolved shear stress (CRSS) of different slip systems in alpha', which will improve its plastic deformation ability. Next, the volume fraction, size and lattice constant of the remnant beta phase will be modified by in-situ heat treatment with synchrotron radiation diffraction. Finally, in-situ tensile experiment with synchrotron radiation diffraction will be performed to obtain the mechanical properties of the above materials and to elucidate the micro-deformation mechanisms according to the information of lattice strain and peak width development. Based on these results, new SLM Ti alloys with enhanced plasticity will be developed.