Mo含量对激光增材制造TC4钛合金组织与性能影响

Effect of Mo Content on Microstructure and Properties of Laser Additive Manufactured TC4 Alloy

摘要:

TC4钛合金因其出色的力学性能和优异的生物相容性，在航空航天及医疗器械领域具有广泛的应用。激光增材制造（LAM）是钛合金成形制造的重要手段，增材制造TC4钛合金内部存在大量的柱状晶和针状的马氏体，会导致材料性能存在各向异性、塑性降低。本研究采用添加钼（Mo）对增材制造TC4钛合金进行组织性能调控，旨在探究Mo含量对激光增材制造TC4钛合金的组织结构和性能的影响。结果表明：适量的Mo含量能有效细化晶粒，随Mo元素的添加，合金基体中逐渐析出TiAl₃相，其含量随Mo含量的增加而增多，当Mo含量达到8wt%，合金中分布着细小弥散的片层状组织，β相的含量急剧增加，晶粒细化程度和位错密度均达到最大值。随Mo含量从0增加到10wt%，合金的抗拉强度、硬度呈先增大后减小趋势，伸长率先减小后增大，杨氏模量逐渐降低，而耐腐蚀性能呈先上升后下降趋势。当Mo含量为8wt%，合金获得最佳的强度与塑性匹配，抗拉强度、伸长率和杨氏模量值分别为1065.6 MPa、11.5%和55.4 GPa，合金耐腐蚀性能有所提升。综合考虑，TC4-8Mo试样有着优良的力学性能和良好的耐腐蚀性能，具有做人体医学植入物材料的潜力。

Abstract:

Due to the excellent mechanical properties and outstanding biocompatibility, TC4 titanium alloy has been widely used in the aerospace and medical device field. Laser additive manufacturing (LAM) is an important technique for fabricating titanium alloys. The presence of large numbers of columnar crystals and acicular martensite in additive manufactured TC4 titanium alloy results in anisotropy and reduced plasticity. In this work, molybdenum (Mo) was added to tailor the microstructure and properties of additive manufactured TC4 titanium alloy, with a specific focus on the effect of Mo content. The results show that an appropriate Mo content can effectively refine the grains. Furthermore, with the addition of Mo element, the TiAl₃ phase is gradually precipitated from the alloy matrix, and its content is increased with the increase in Mo content. When the Mo content reaches 8wt%, a fine and dispersed lamellar structure is distributed in the alloy, and the β-phase content increases sharply. In addition, the maximum degrees of grain refinement and dislocation density are obtained. As Mo content increase from 0 to 10wt%, the tensile strength, hardness and corrosion resistance of the alloy increase first and then decrease, whereas the elongation shows the opposite trend. Concurrently, the Young's modulus gradually decreases. When Mo content is 8wt%, the alloy achieves the best mechanical properties: a tensile strength of 1065.6 MPa, an elongation of 11.5% and Young's modulus of 55.4 GPa. Additionally, its corrosion resistance is improved. Overall, TC4-8Mo sample has excellent mechanical properties and superior corrosion resistance, demonstrating high potential for use in human medical implant.