硼含量对激光熔覆沉积TC4钛合金显微组织与力学性能影响

Effect of different Boron content on microstructure and mechanical property of TC4 titanium alloy fabricated by laser cladding deposited

摘要:

基于航空航天领域对高比强度、耐高温以及耐磨损钛合金材料的迫切需求，本文采用激光熔覆沉积(Laser Cladding Deposition, LCD)技术制备出含硼(B)的TC4钛合金复合材料，并研究了B元素含量对其显微组织和力学性能的影响。结果表明，随着B元素含量增加，可以显著降低LCD成形TC4钛合金的晶粒尺寸，其晶粒尺寸从1294μm降低至28.6μm，在硼元素作用下也逐渐弱化了LCD技术导致的柱状晶现象；当B含量较低时，TC4钛合金LCD成形过程中生成的TiB主要在原始β晶界处富集，随着B元素含量增加，针状TiB逐渐在晶粒内部析出。在LCD成形TC4钛合金复合材料性能方面，随着B含量增加，合金的硬度与强度也逐渐增大，显微硬度从313.23 HV增大至359.24 HV，抗拉强度由848 MPa增加至1119.5 MPa，提升了32.02%。本文研究为增材制造复杂结构高性能钛基合金构件在航空航天领域的应用提供理论支撑。

Abstract:

There is an urgent demand in aerospace applications to develop titanium alloy materials with high specific strength, high-temperature resistance, and wear resistance. Hence, the TC4 titanium alloy composite material was developed through fabrication by laser cladding deposition (LCD) technology, and the effect of boron (B) content on its microstructure and mechanical properties was studied. The results show that the B element can significantly reduce the grain size of the TC4 titanium alloy as fabricated by LCD. The increment of B content exhibits grain size reduction from 1294 μm to 28.6 μm with 1% wt B content, which gradually weakens the columnar grain. The TiB acicular becomes precipitate at the β grain boundary as the B content increases. Consequently, the TC4 composite material"s hardness increases from 313.23 HV to 359.24 HV and tensile strength from 848 MPa to 1119.5 MPa. The research in this paper provides theoretical support for the application of additive manufacturing of high-performance platform-based alloy components with complex structures in the aerospace field.