Effect of Modification on Mechanical Behavior of ZA303 under High Temperature

Abstract

In this paper , by SEM、EDS、XRD and Shimadzu AG-I250KN precision universal testing machine , the metallurgical structure, fracture appearance, the mechanical properties of the ZA303 under high temperature were systematically studied .The results shows that :The microstructure of ZA303 at room temperature are : α phase + (α＋η) eutectoid + ε phase + η phase. After adding modifying elements B、Ti in ZA303：the microstructure of the alloy is from gross dendrites to uniform equiaxed grains , the quantity, morphology and distribution of the (α + η) have greatly change: the quantity of (α + η) is less, from a continuous network to intermittent block, and its end become blunt, or even cylindrical horn and dispersed distribution; on the grain boundary, the size of ε phase become smaller and dispersed distribution, the number of mesh ε phase reduced but intermittent strips increased; adding B、Ti have a good effect of restraining Al element segregation，so the foundry defects decreased obviously. In the range of experimental temperature, the increase of ductility is large while the tensile strength is small: at the same time, the mechanical performances stability is better than that without modification.