Effect of HIP temperature on the microstructure and properties of Be-Al alloys

The effect of HIP-temperature on the tensile properties and fracture mechanism of a powder metallurgical (PM) Be-Al alloy based alloy has been investigated in this study. Prealloyed, the PM Be-Al alloy are fabricated with the HIP temperature of 700°C and 900°C. The tensile tests and scanning electric microscopy (SEM) in situ fatigue observations of Be-Al alloy have been conducted. The results of present study indicate that the alloy HIP´ed at 700°C exhibited higher ultimate tensile strength and lower ductility than that of the alloy HIP´ed at 900°C under tension loading. Fatigue tests showed that the former has higher fatigue strength and fatigue resistance than the latter. All fatigue fracture surface observed by SEM are characterized by the faceted crystallographic cleavage planes in Be phases surrounded by shear or tear-induced ductile fracture of Al phases. Characteristic fatigue striations in Be grain interior of the alloy HIP´ed at 700°C can be seen while the alloy HIP´ed at 900°C has many interlaced strips along the interfaces between Be and Al phase.