Fe含量对增材制造TC4钛合金组织与性能的影响

Effect of Fe Content on the Microstructure and Properties of Additively Manufactured TC4 Titanium Alloy

摘要:

通过激光熔化沉积（laser melting deposition，LMD）钛基粉末制备出成型致密且无组织缺陷的沉积态试样，研究Fe含量对沉积态TC4钛合金试样的微观组织、相的种类与含量和力学性能的影响规律。结果表明：随着Fe的加入，α-Ti的尺寸减小，网篮组织得到细化，沉积态试样在成型方向上由粗壮的柱状晶转变成细小均匀的等轴晶。其中加入3wt% Fe试样的平均晶粒尺寸最小为160.6 μm，相较于未添加Fe的试样减小约76%；结合XRD结果可得，试样的微观组织均由较多的α-Ti和少量的β-Ti组成，随着Fe的加入，β-Ti含量略有增加；添加Fe能够显著提高试样的拉伸性能，其中加入3wt% Fe试样的抗拉强度和屈服强度与TC4相比分别提高了15.5%和18.0%，断后延伸率提高约60%，然而添加Fe的沉积态试样的冲击韧性略有下降。

Abstract:

Densely moulded sedimentary specimens without tissue defects were prepared by laser melting and deposition of titanium-based powders. The effects of Fe content on the microstructure, phase type and content and mechanical properties of TC4 specimens in the as-deposited state were investigated. The results show that with the addition of Fe, the size of α-Ti decreases, the net-basket microstructure is refined, and the as-deposited specimens are transformed from robust columnar crystals to fine and uniform equiaxial crystals in the forming direction. The average grain size of the specimen with 3wt% Fe is 160.6 μm, which is about 76% smaller than that of the specimen without added Fe. Combined with the XRD results, it can be obtained that the microstructure of the specimen consists of a large amount of α-Ti and a small amount of β-Ti, and the content of β-Ti increases slightly with the addition of Fe. The addition of Fe can significantly improve the tensile properties of the specimens, in which the tensile strength and yield strength of 3wt% Fe specimens are increased by 15.5% and 18.0%, respectively, and the post-break elongation is increased by about 60% compared with those of TC4. However, the impact toughness of the specimens in the as-deposited state with the addition of Fe is slightly decreased.