放电等离子体烧结Al-4.5Cu合金的组织与性能

The microstructure and mechanical properties of Al-4.5Cu alloy fabricated by spark plasma sintering

利用放电等离子烧结制备Al-4.5Cu(质量分数,%)合金,并对其进行固溶、淬火和时效处理。通过X射线衍射、扫描电镜和透射电镜进行结构表征以及拉伸力学性能测试,研究颗粒界面结构和界面析出行为及其对力学性能影响。结果表明:放电等离子烧结Al-4.5Cu合金颗粒界面由Al_(2)O_(3)纳米颗粒、粗大CuAl_(2)相和纳米微孔组成。热处理后,Al-4.5Cu合金颗粒界面附近析出尺寸为150-600 nm的CuAl_(2)相,同时形成宽度为40-60 nm的无析出区。屈服强度和抗拉强度分别从95 MPa和229 MPa增加至280 MPa和378 MPa,断后伸长率从11.8%下降为6.0%。强度增加主要归因于热处理过程中析出相的弥散分布,以及材料的致密化;塑性下降主要是由于拉伸变形过程中,无析出区率先发生塑性变形,导致位错从无析出区向颗粒界面附近的CuAl_(2)相堆积,造成应力集中,促使裂纹沿颗粒界面扩展,材料伸长率下降。

Al-4.5Cu (mass fraction,%) alloy was prepared by spark plasma sintering (SPS) followed by solution,quenching and aging.The X-ray diffraction,scanning electron microscopy,transmission electronmicroscopy and tensile tests were carried out.The effect of interparticle boundary (IPB) and precipitation behavior on mechanical properties of the Al-4.5 Cu alloy were investigated in detail.The results show that the IPB consists of Al_(2)O_(3) nanoparticles,CuAl_(2)phase and residual nanopores.After T6 aging,coarse CuAl_(2)phases with a diameter of 150-600 nm precipitate at the IPB,and the precipitation free zone (PFZ) with a width of 40-60 nm is formed.An improvement of yield strength and ultimate tensile strength from 95 MPa and 229 MPa to 280 MPa and 378 MPa is achieved respectively after T6 aging,while the elongation to fracture decreases from 11.8% to 6%.The increase in strength is mainly due to the well dispersion of precipitates and the densification of the material during T6 aging.The decrease in plasticity may result from the earlier plastic deformation in the PFZ during tensile deformation,leading to the accumulation of dislocations from PFZ to CuAl_(2)phase nearby the IPB,as a result,stress concentrationis formed,which consequently promotes cracksexp and along the IPB and decreases the ductility of the material.