采用"T"型模具实验和差热分析法研究了稀土元素钇(Y)含量对Al-20Si-3Cu合金热裂敏感性的影响,结合X射线衍射(XRD)、能谱仪(EDS)、电子显微探针分析(EPMA)等方法分析凝固过程中相析出及其对合金热裂的影响,并用Clyne 和Davis模型对合金的热裂敏感性进行了预测.结果表明:用热裂敏感系数(CSC)预测的合金热裂敏感性趋势与实验结果一致;Y的加入使合金中形成一些新的第二相,同时减少粗大初晶Si的数量,降低合金的热裂敏感性;当Y质量分数达到1%时,合金的热裂敏感性达到最小值.同时运用ProCAST软件对Al-20Si-3Cu-xY系合金的凝固过程的温度场和应力场进行了模拟,热裂指标的模拟结果与实验结果吻合良好.
The effect of rare earth element Y content on the hot tearing susceptibility of Al-20Si-3Cu alloy was studied by means of"T"mold experiment and differential thermal analysis(DTA).The phase precipitation behavior and its effect on hot tearing of alloys during the solidification process were analyzed by X-ray diffraction(XRD),energy dispersive spectrometer(EDS),electron probe microanalysis(EPMA).The Clyne and Davis model was used to predict the hot tearing susceptibility of the alloy.The results indicate that the trends of hot tearing susceptibility predicted by the crack sensitivity coefficient(CSC)show no difference from that tested by experiments.The addition of Y makes new phases appear in alloys,reduces the amount of coarse primary Si and decreases the hot tearing susceptibility.When the mass fraction of Y is 1%,the alloy has the lowest hot tearing susceptibility.Mean while,ProCAST was used to simulate the filling process and solidification process.It turns out that the simulation results of the hot tearing indicator and stress are consistent with the experimental results.