摘要
An innovative semisolid technique termed as vibrating cooling slope(VCS)has been applied to producing in-situ Al-25%Mg2Si(mass fraction)composite.The molten Al-16.5Mg-9.4%Si(mass fraction)alloy with 100°C superheat was poured on the surface of an inclined copper plate(set at 45°inclined angle)while it was vibrated at a frequency of 40 Hz and an amplitude of 400μm.After travelling the length of 40 cm on the slope,the resultant semisolid alloy was cast into a steel mold.For the purpose of comparison,reference composite samples were made by gravity casting(GC)and conventionally still cooling slope casting(CS)methods using the same alloy under identical conditions.The samples were hot extruded at 500°C.It was concluded that the size of Mg2Si particles was decreased by about 50%and 70%for the CS and VCS produced samples respectively when compared to that of the GC produced sample.Despite of their higher porosity contents,both the as-cast and hot-extruded VCS processed samples exhibited higher hardness,shear yield stress(SYS)and ultimate shear strength(USS)values as compared with their GC produced counterparts.These results were attributed to the refined and modified microstructure obtained via this newly developed technique.
采用被称为振动斜板冷却法(VCS)的一种新型半固态成型技术制备Al-25%Mg_2Si原位复合材料。将熔化的Al-16.5%Mg-9.4%Si合金(过热100°C)浇铸到振动的倾斜铜板表面(倾斜角为45°),其振动频率为40 Hz,振幅为400μm。在斜板上移动40 cm后,将合成的半固态合金铸入钢模中。为了对比,采用重力铸造法(GC)和传统的静止斜板冷却浇铸法(CS)制备合金成分相同的复合材料。将复合材料样品在500°C进行热挤压。与GS制备的合金相比,采用CS和VCS制备的合金中Mg_2Si颗粒尺寸分别减小了50%和70%。与GC制备的样品相比,VCS制备的浇铸态和热挤压态样品,尽管其孔隙率较大,但具有更高的硬度、剪切屈服应力(SYS)和剪切极限强度(USS),这是由于通过这种新型的VCS方法可以得到更细小的微观组织。
