A new laser melting deposition (LMD) method was employed for Ti6Al4V to stimulate the columnar to equiaxed transition (CET) via adding 1 wt% ~ 5 wt% nano-sized B₄C particles. Results indicate that the grains were signifcantly refined from 600 μm to 11 μm with the increasing content of B₄C; When the B₄C content was 3 wt%, the B₄C/Ti6Al4V composite achieved CET; TiB and TiC reinforcements were produced by in-situ reaction between the Ti6Al4V and B₄C, which not only precipitated at the grain boundaries to restrict the grain growth, but also acted as nucleation sites to accelerate the non-spontaneous nucleation of β grains to achieve fine grain strengthening. Tensile tests show that adding 3 wt% B₄C particles results in a signifcantly increased yield strength (1235 MPa) and tensile strength (1310 MPa) and maintains a certain amount of ductility (2.4% elongation). And the epitaxial growth of β grains in the underlying deposited layer and the CET mechanism with successive layer-upon-layer deposition were analyzed.

Ti6Al4V采用一种新的激光熔融沉积（LMD）方法，通过添加1 wt％〜5 wt％的纳米级B ₄ C颗粒来激发柱状至等轴转变（CET）。结果表明，随着B ₄ C含量的增加，晶粒从600μm细化到11μm 。当B ₄ C的含量为3重量％时，B ₄ C / Ti 6 Al ₄ V复合材料达到CET。通过Ti6Al4V和B ₄ C之间的原位反应生成TiB和TiC增强材料，它们不仅在晶界处沉淀以限制晶粒生长，而且还充当成核位点，以促进β晶粒的非自发成核。实现细晶粒强化。拉伸试验表明，添加3 wt％的B ₄C颗粒导致屈服强度（1235 MPa）和抗张强度（1310 MPa）显着提高，并保持一定的延展性（2.4％伸长率）。并分析了底层沉积层中β晶粒的外延生长以及逐层逐层沉积的CET机理。