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使用直接能量沉积技术,以纯Ti、纯V和纯Cr粉末为原料制备一系列Ti-YV-15Cr(X=20,25,30,35)合金.研究了V含量对Ti-XV-15Cr合金的晶粒形貌、显微硬度、弹性模量及阻燃性能的影响.结果表明,Ti-20V-15Cr、Ti-25V-15Cr和Ti-30V-15Cr合金的显微组织由外延生长的柱状晶和顶部细小的等轴晶组成,随着V含量的增加,柱状晶粒的长/宽比逐渐减小.而Ti-35V-15Cr合金的显微组织与Ti-20V-15Cr,Ti-25V-15Cr和Ti-30V-15Cr有很大的不同,除了顶部是细小的等轴晶,几乎全由近等轴晶组成.结合柱状晶向等轴晶转变(CET)模型以及柱状晶层的高度与Z轴抬升量(△Z)之间的关系,解释了微观组织的形成机理.Ti-XV-15Cr合金的平均显微硬度随V含量的增加而略有增加,其弹性模量在123.8与137.6GPa之间.阻燃测试表明,Ti-35V-15Cr合金具有最佳的阻燃性能.“,”A series of Ti-AV-15Cr(X=20,25,30,35,wt％)alloys were prepared by directed energy deposition(DED)technique,where pure Ti,pure V,and pure Cr powders were used as raw materials.The effects of V content on grain morphology,microhardness,elastic modulus and the flame-resistant properties of Ti-AV-15Cr alloys were investigated.It is found that the microstructures of Ti-20V-15Cr,Ti-25V-15Cr and Ti-30V-15Cr alloys are composed of columnar grains growing epitaxially and fine equiaxed grains at the top region,and the aspect ratio of the columnar grains decreases gradually with increasing the V content.The microstructure of Ti-35V-15Cr alloy is composed of near-equiaxed grains except at the very top region,which is very different from the microstructure of Ti-20V-15Cr,Ti-25V-15Cr and Ti-30V-15Cr alloys.The formation mechanism of microstructure is explained by combining the columnar to equiaxed transition(CET)model and the relationship between the height of the columnar grains layer and Z axis increment(△Z).The average microhardness of Ti-XV-15Cr alloys increases slightly with increasing the V content,and the elastic modulus is between 123.8 and 137.6 GPa.Flame-resistant test shows that Ti-35V-15Cr alloy exhibits the best flame-resistant properties.