Fatigue Property for the Powder Metallurgy Beryllium-Aluminum Composite Materials

摘要

Two powder metallurgy (PM) beryllium-aluminum (BeAl) composite materials were fabricated under hot isostatically pressing (HIP) temperatures 700 ℃ (BeAl-700) and 900 ℃ (BeAl-900). BeAl-700 exhibited higher ultimate tensile strength and lower ductility than BeAl-900 under tension loading. Fatigue tests showed that the former has higher fatigue strength and fatigue resistance than the latter. All fatigue fracture surfaces observed by the scanning electric microscopy (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 BeAl-700 can be seen while BeAl-900 has many interlaced strips along the interfaces between Be and Al phase. As Al is much softer than Be, localized microscopic plastic flow begins with the Al phase.