中文摘要：

粉末的团结微观结构喂了激光添加剂生产 Ti6Al2Zr2Sn3Mo1.5Cr2Nb 钛合金被调查。结果由故意增加粉末显示出那喂率，部分融化的粉末在熔融的水池的顶被保留，它能支持异构的原子核。因此，每 cladding 层由二个区域组成：(i) 随机面向了部分融化的粉末在每 cladding 层的顶引起的细胞的结构区域；并且(ii ) 邻近熔化线的取向附生的细胞的结构区域。通常，随机面向了细胞的结构区域完全是为大量过程条件的 remelted。remelting 效果保证细胞的结构的取向附生的生长的连续性并且导致圆柱的谷物的形成。为了获得 equiaxed 谷物，扫描速度和粉末喂率应该小心地被选择扩大随机面向的细胞的结构区域。

英文摘要：

Solidification microstructure of powder fed laser additive manufactured Ti-6Al--2Zr--2Sn--3Mo--1.5Cr--2Nb titanium alloy was investigated, The results showed that by deliberately increasing the powder feed rate, partially melted powders were retained at the top of the molten pool, which can promote heteroge- neous nucleus. Thus, each cladding layer is composed of two regions： （i） randomly orientated cellular structure region caused by partially melted powders at the top of each cladding layer; and （ii） epitaxial cellular structure region adjacent to the fusion line. Usually, randomly orientated cellular structure region was totally remelted for a wide range of process conditions. The remelting effect ensures the continuity of epitaxial growth of cellular structure and leads to the formation of columnar β grains, In order to obtain equiaxed grains the scanning velocity and powder feed rate should be carefully selected to enlarge the randomly orientated cellular structure region,