材料工程外文翻譯--mg-9al-1zn合金的半固體擠壓成型

1、Semisolid extrusion moldingof Mg-9%Al-1%Zn alloysF. CZERWINSKIDevelopment Engineering, Husky Injection Molding Systems Ltd., Bolton,Ontario, L7E 5S5, CanadaA novel technique in manufacturing net-shape components of magne

2、sium alloys, which combines semisolid processing, extrusion and injection molding, is outlined. For an Mg-9%Al-1%Zn composition, the high-temperature transformations and factors controlling solidification microstructure

3、s, are analyzed. C _ 2004 Kluwer Academic Publishers1. IntroductionExtrusion is the plastic deformation process by which a metal is forced to flow by compression through the die orifice of a smaller cross-sectional area

4、than that of the original billet. Since the material is subjected to compressive forces only, the extrusion is an excellent method for breaking down the cast structure of the billet with little or no cracking [1]. Most m

5、etals are extruded hot when the billet is preheated to facilitate plastic deformation, but room temperature (cold) extrusion is also exercised. So far, conventional extrusion applications do not utilize preheating materi

6、als above the solidus temperature to enter the semisolid range.The advantages of processing metallic alloys in a semisolid state are attributed to the globular solid particles which control their thixotropic properties a

7、t high temperatures and reduce the content of dendritic forms after subsequent solidification [2]. It is well established that the benefits associated with semisolid processing, such as low shrinkage porosity, high toler

8、ances and energy savings, are more evident at high solid fractions. Moreover, the ability to cast at higher solid fractions is of interest in improving billet stability and minimizing material loss during handling.Of all

9、 semisolid technologies, injection molding provides the largest flexibility in terms of the processed solid contents [3]. This feature is attributed to the fact that injection molding combines the slurry making and compo

10、nent forming operations into one step, and the slurry is accumulated in a direct vicinity of the mold gate. So far, these potentials are not explored and commercial applications are limited to liquid-rich slurries, which

11、, for thin-wall sections, may contain solid volumes as low as 5–10%. As the major obstacle preventing using high solid contents, the premature alloy’s freezing and incomplete filling the mold cavity, is reported [4]. It