摘要
An advanced rheomoulder,which is a device in the integration of melting metal,storage,slurry preparation,transportation and injection forming,was introduced and used to manufacture rheomoulding AZ91 D alloy.Effects of pouring temperature and cylinder temperature on microstructures and mechanical properties of rheomoulding AZ91 D alloy were investigated.The results show that the process can obtain such rheomoulding AZ91 D in which primary α-Mg particles are fine,spherical and uniformly distributed in the matrix.With the decrease of pouring temperature,the morphology of primary α-Mg particles changes from coarse rosette-like to fine spherical shape gradually.As the cylinder temperature decreases,the average size of primary α-Mg particles decreases firstly and then substantially maintains stable while the sphericity and solid fraction increase continuously.Also,decreasing pouring temperature or cylinder temperature properly contributes to improving mechanical properties of rheomoulding AZ91 D for the refinement of α-Mg particles and the decrease of porosity fraction.Furthermore,rheomoulding AZ91 D performs much better than thixomoulding,rheo-diecasting and high pressure die-casting（HPDC） in terms of mechanical properties.Compared with HPDC,the tensile strength,yield strength and elongation are increased by 27.8%,15.7% and 121%,respectively.
介绍一种先进的集金属熔化、储存、浆料制备、浆料输送和注射成形于一体的流变注射成形机,并使用该设备生产一批AZ91D镁合金流变注射成形件。研究浇注温度和缸体温度对AZ91D镁合金流变注射成形件组织和力学性能的影响规律。结果表明,流变注射成形工艺可以成功获得初生α-Mg颗粒细小、圆整、均匀分布于基体组织中的AZ91D镁合金成形件。随着浇注温度的下降,初生α-Mg形貌由粗大的蔷薇状逐渐转变为细球状。随着缸体温度的降低,初生α-Mg颗粒的尺寸先下降,之后基本保持不变,其球形度和固相率不断提高。同时,适当地降低浇注温度或缸体温度可以细化α-Mg颗粒和降低孔隙率,这有助于流变注射成形件力学性能的提高。另外,AZ91D镁合金流变注射成形件在力学性能上优于触变注射成形、流变压铸成形和高压铸造。与高压铸造相比,AZ91D镁合金流变注射成形件的抗拉强度、屈服强度和伸长率分别提高了27.8%、15.7%和121%。
基金
Project(2011CB606302-1)supported by the National Basic Research Program of China
Project(2013AA031001)supported by High-tech Research and Development Program of China
