Si元素掺杂对AlTiV轻质多主元合金微结构及硬度的影响

Effect of Silicon Element Doping on the Microstructure and Microhardness of AlTiV Lightweight Multi-Principal Element Alloys

摘要:

采用真空感应熔炼技术制备了Al₂₀(TiV)_80－xSi_x (x=0、0.7)轻质多主元合金。利用X射线衍射仪、扫描电子显微镜、透射电子显微镜和显微硬度计等表征合金的微观结构与力学性能，研究了Si元素掺杂以及均匀化退火对合金微观组织结构及显微硬度的影响。结果表明：铸态合金为单相BCC结构，并且晶粒粗大；退火后，有序B2相从合金基体中析出，提高了合金的硬度；Si元素的加入，促使合金晶粒尺寸减小，抑制了B2相长大。合金显微硬度最高为587 HV，比强度达到430 MPa·cm³·g^-1。分析表明，合金的高显微硬度主要来源于合金的固溶强化、第二相沉淀以及高点阵阻力。

Abstract:

In this work， Al₂₀（TiV）_80－xSi_x （x=0，0.7） lightweight multi-principal element alloys were fabricated by induction melting. The microstructure and mechanical properties of the alloys were characterized by X-ray diffractometer， scanning electron microscope， transmission electron microscope and microhardness tester， and the effects of Si doping and homogenization annealing on the microstructure and microhardness of the alloys were investigated. The results show that the as-cast alloys are single BCC phase with coarse grains. After annealing， the ordered B2 phase precipitates from the matrix of alloys， which improves the microhardness of the alloys. The doping of silicon elements reduces the grain size of the alloys and restrains the precipitation of B2 phase. The microhardness of the alloys were tested up to 587 HV， and the specific yield strength reaches 430 MPa·cm³·g^-1. According to the analysis， the high microhardness of the alloys mainly comes from the solid solution strengthening， second phase precipitation and lattice resistance of the alloys.