Thermal stabilities of microstructures and mechanical properties of rapidly solidified AlCrYZr aluminium alloy

Using of optical microscopy, X-ray diffraction (XRD), transmission electron microscopy(TEM), hardness and tensile testing, the effect of thermal exposure at high temperatures on the microstructures and of high-temperature tensile properties (including thermal stability) of rapidly solidified AlCrYZr have been studied. The results show that there are two main phases, Al20 Cr2Y (cubic, a = 1.437 nm) and DO23Al3Zr(terganal, a = 0.4 013 nm, c = 1.732 nm), in the as-solidified alloy. The Al20Cr2Y phase can maintain its cubic structure at 500°C, but the particles coarsen remarkably and even become lumpish. In coarse lumpish Al20Cr2Y phase the plane faults and twin structures exist. The hardness of the alloy increases during thermal exposure due to precipitation of Li2Al3Zr from the solid solution. The microstructural and tensile results indicate that the alloy may be used stably at least below 350°C.