稀土AlMg3W合金的研制

在研制稀土AlMg3W合金的基础上．采用金相观察、X射线衍射等手段，并通过力学性能、耐磨性能、焊接性能、热膨胀性能等对比测试，系统地分析了稀土对AlMg3W合金显微结构及物理性能的影响。结果表明，当稀土含量为0．05％时，稀土AlMg3W合金的性能最佳。

AlMg/Al_2O_3粉芯丝材电弧喷涂的粒子和涂层特征

目的研究AlMg/Al_2O_3粉芯丝材电弧喷涂的飞行粒子、扁平粒子、涂层结构及涂层抗冲击性能。方法研制了2种含微米级Al_2O_3粉料的铝基粉芯丝材,利用扫描电镜对收集到的电弧喷涂过程中形成的飞行粒子、扁平粒子以及喷涂层的微观结构进行表征。采用自制的循环冲击设备测试了涂层的抗冲击性能。结果 AlMg/Al_2O_3粉芯丝材电弧喷涂过程中形成了含有铝镁、铝镁包覆氧化铝、氧化铝3种不同类型的飞行粒子,添加的Al_2O_3粒径越小,铝镁包覆氧化铝飞行粒子中的铝镁膜增厚,所包覆的Al_2O_3颗粒越多。喷涂形成的扁平粒子形状复杂多样,表面不平坦,有溅射现象。制备的涂层结构致密、缺陷少,Al_2O_3粉料粒径范围为400~500μm和30~50μm制备的AlMg/Al_2O_3涂层表面的Al_2O_3颗粒平均面积含量分别为5.52%、13.54%,说明添加小粒径Al_2O_3颗粒的涂层中残留的Al_2O_3颗粒增多。在500次循环冲击试验下,AlMg涂层和AlMg/Al_2O_3涂层没有明显的径向、环形裂纹和大面积剥落现象,但存在明显的塑性变形。结论随着添加的微米级Al_2O_3颗粒粒径的减小,涂层中Al_2O_3颗粒的含量增加。制备的AlMg/Al_2O_3涂层以塑性变形吸收了大部分冲击功,降低了冲击疲劳裂纹产生的可能性,涂层与基体保持良好的结合状态。

Semisolid metal forming by, novel sloping plate process

Semisolid metal forming by a novel sloping plate process was studied. A sloping plate with wavelike surface was used to prepare semisolid alloy. Semisolid billets and slurries with good microstructures and excellent property were prepared by cooling or preheating the sloping plate. During preparing semisolid alloy by the proposed process, the co-action of burst nucleation and dendrite fragmentation causes fine spherical microstructure formation, and casting temperature, cooling strength and sloping angle are the main factors influencing the alloy microstructure. Under the current experimental conditions, in order to prepare good quality semisolid billets, proper casting temperature ranges of 660-690℃for AlMg3 alloy and 660-680℃for AlSi6Mg2 alloy are suggested. A small car hub wheel of AlSi6Mg2 alloy was thixoformed, and its pattern and inner microstructure are fine. The reasonable technological conditions for preparing AlSi6Mg2 slurry are also proposed: the sloping plate preheating temperature is 300℃, and the casting temperature is 680℃.