工艺参数对激光定向能量沉积B4C/Ti6Al4V复合材料组织及性能的影响

Effect of Process Parameters on Microstructure and Properties of B4C/Ti6Al4V Composites Fabricated by Laser Directed Energy Deposition

摘要:

为研究工艺参数（激光功率、扫描速度）对激光定向能量沉积1vol% B₄C/Ti6Al4V复合材料组织与力学性能的影响，揭示不同工艺参数下组织与力学性能的关系，采用激光定向能量沉积技术制备了不同工艺参数的B₄C/Ti6Al4V复合材料。实验结果表明：外加的B₄C颗粒发生部分溶解，复合材料的增强体由未溶B₄C、TiB和TiC组成。随着激光功率的增加或扫描速度的降低，未溶B₄C的数量减少，原位生成的TiB和TiC数量增多，β-Ti的晶粒尺寸逐渐增大。复合材料的硬度随着激光功率的升高从382.6 HV_0.5增加至406.5 HV_0.5，扫描速度降低时硬度也呈上升趋势。激光功率为1200 W，扫描速度为 500 mm/min时磨损率达到最低为8.517×10^–4 mm³·N^–1·m^–1。激光功率减小或者扫描速度增大时，抗拉强度增加，最高可达1180.4±6.2 MPa。抗拉强度的提升可归因于晶粒细化的作用。

Abstract:

Laser directed energy deposition technique was used to prepare 1vol% B₄C/Ti6Al4V composites with varying process parameters to investigate the effects of process parameters (laser power and scanning speed) on the microstructure and mechanical properties of laser melting deposited B₄C/Ti6Al4V composites and to uncover the relationship between the microstructure and mechanical properties of the composites under different process parameters. The results show that the reinforcement of the composites consists of undissolved B₄C, TiB, and TiC since the additional B₄C particles are partially dissolved. As the laser power rises or the scanning speed drops, the quantity of undissolved B₄C diminishes. Simultaneously, the quantities of in-situ formed TiB and TiC increase, and the grain size of β-Ti gradually grows. As laser power increases, the hardness of composites rises from 382.6 HV_0.5 to 406.5 HV_0.5. As scanning speed decreases, the hardness of composites likewise rises. The wear rate achieves a minimum value of 8.517×10^–4 mm³·N^–1·m^–1 when the laser power is 1200 W and the scanning speed is 500 mm/min. When the laser power drops or the scanning speed rises, the tensile strength rises, reaching a maximum value of 1180.4±6.2 MPa. The effect of grain refinement is responsible for the increase in tensile strength.