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通过场发射扫描电子显微镜及能谱分析、光学显微镜、X射线衍射分析、室温拉伸试验及布氏硬度测试等手段研究了球化温度对AZ91HP镁合金显微组织和力学性能的影响。结果表明,退火处理后,铸态AZ91HP合金组织中粗大离散的共晶相消失,在其后的随炉缓冷过程中以层片状形式弥散,均匀分布于α-Mg基体;球化过程中,层片状β-Mg_(17)_Al_(12)相自身溶断;球化温度在300℃时球化效果最好;硬度值随球化温度的升高先缓慢上升后下降,且高于铸态合金;经300℃保温20 h球化处理后,合金的抗拉强度、屈服强度达到最大值242.7、132.6 MPa,分别比铸态合金提高了21.78%、28.86%,伸长率较铸态提高了57.47%。
The effect of spheroidizing temperature on the microstructure and mechanical properties of AZ91HP magnesium alloy was studied by field emission scanning electron microscopy and energy dispersive spectroscopy, optical microscopy, X-ray diffraction analysis, room temperature tensile test and Brinell hardness test. The results show that the coarse and dispersed eutectic phase disappears in the as-cast AZ91HP alloy after annealing and disperses in the form of lamella in the subsequent slow cooling of the furnace and is uniformly distributed in the α-Mg matrix. During the spheroidization , The lamellar β-Mg_ (17) _Al_ (12) phase dissolves itself; the spheroidization effect is best at 300 ℃; the hardness increases slowly and then decreases with the increase of the spheroidizing temperature, State alloy. After 20 h spheroidizing treatment at 300 ℃, the tensile strength and yield strength of the alloy reached the maximum value of 242.7 and 132.6 MPa, respectively, 21.78% and 28.86% higher than that of the as-cast alloy, respectively. The elongation was higher than that of the as-cast 57.47%.