TiB2颗粒诱导AlSi5电弧增材微观组织演变及性能研究

铝合金的电弧增材制造过程中因持续热积累而引起组织分布不均匀和溶质偏析,导致其性能各向异性。针对这一问题,设计了TiB₂纳米颗粒添加铝合金的钨极氩弧(Tungsten inert gas,TIG)增材制造工艺。在电弧增材制造过程中,通过表面预涂层的方式将纳米TiB₂颗粒添加到试样中,对比研究了纳米TiB₂颗粒不同质量分数对AlSi5合金微观组织的影响。结果表明,随着TiB₂质量分数的增加,AlSi5合金的微观组织不均匀性得到明显改善,1.5%TiB₂的添加使AlSi5合金的晶粒尺寸从226μm减小到85.6μm,且引起(110)和(112)基面上的织构明显减弱,最大取向密度呈下降的趋势;与无颗粒添加的AlSi5增材试样相比,颗粒添加后的沉积层硬度与弹性模量均得到显著提高,硬度值从879MPa增加到1253MPa,弹性模量从81.9GPa增加到88.3GPa。

Microstructural Evolution and Mechanical Property of TiB2Nanoparticles Reinforced AlSi5 Alloy in Wire and Arc Additive Manufacturing

In the process of arc additive manufacturing,aluminum alloy is easy to cause inhomogeneous microstructure distribution and solute segregation due to continuous heat accumulation,leading to its anisotropic properties.In order to solve this problem,the tungsten inert gas(TIG)additive manufacturing process with addition of TiB₂nanoparticles was designed.In the process of wire and arc additive manufacturing,TiB₂nanoparticles were added to the deposition samples by surface pre-coating.The effects of different mass fraction of TiB₂nanoparticles on the microstructure of AlSi5 alloy were compared and studied.The results show that the microstructure inhomogeneity of AlSi5 aluminum alloy was obviously improved with the mass fraction of TiB₂increased.The grain size decreased from 226μm to 85.6μm with the addition of 1.5%TiB2,and the texture on(110)and(112)basal planes decreased obviously,besides the maximum orientation density was decreased.The hardness and elastic modulus of the deposited layer were significantly improved with addition of TiB₂nanoparticles.The value of hardness increased from 879MPa to 1253MPa,and the elastic modulus increased from 81.9GPa to 88.3GPa.