激光立体成形Ti-xV-15Cr (x = 20,25,30,35)合金的组织和阻燃性能

Microstructure and Flame-resistant Properties of Ti-xV-15Cr (x = 20,25,30,35) Alloys by Laser Solid Forming

摘要:

本文详细介绍了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-xV-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(ΔZ)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 GPa到137.6 GPa之间。阻燃测试表明，Ti-35V-15Cr合金具有最佳的阻燃性能。

Abstract:

This paper details the production of a series of Ti-xV-15Cr (x=20,25,30,35) alloys by directed energy deposition (DED) technology, and 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-xV-15Cr alloys were determined. It was found that the microstructures of Ti-20V-15Cr, Ti-25V-15Cr and Ti-30V-15Cr alloys were composed of columnar grains growing epitaxially and fine equiaxed grains at the top region, with the aspect ratio of the columnar grains decreasing gradually with increasing V content. The microstructure of Ti-35V-15Cr alloy was composed of full near equiaxed grains except the very top region, which is very different from those of Ti-20V-15Cr, Ti-25V-15Cr and Ti-30V-15Cr alloys. The formation mechanism of microstructure was 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 (ΔZ). The average microhardness of Ti-xV-15Cr alloys increases slightly with increasing V content, and the elastic modulus falls between 123.8 GPa to 137.6 GPa. Flame-resistant test showed that Ti-35V-15Cr alloy exhibits the best flame-resistant properties.