Papers by Keyword: β-Mg₁₇Al₁₂ Phase

Abstract: The microstructure and element distribution of AZ80 magnesium alloy as-cast and after annealing treatment were studied by OM, SEM, XRD, EDS and TEM. The results show that the coarse divorced eutectic phase distributed along the grain boundary dissolve into Mg matrix during the isothermal process at 415°C for 24h. During the cooling process of annealing treatment, the lameller-shape β-Mg₁₇Al₁₂ nucleated preferentially in the grain near the boundary, then grows towards the neighbor grains with longitudinal direction, which precipitated from magnesium solid solution as perlite-type precipitation. When cooled to room temperature, the lameller-shape β-Mg₁₇Al₁₂ was uniformly distributed in the matrix, and the lamellar spacing inside β phase is about 1-2μm.

Abstract: The precipitation mechanism of secondary-precipitated phase β in AZ80 magnesium alloy during the hot compression deformation under different temperature was investigated. The results show that there are β-Mg₁₇Al₁₂ phases with different morphology and precipitation mechanism in the microstructure of AZ80 alloy deformed both in two-phase region、critical region and single-phase region. β-Mg₁₇Al12 phases were directly deformed and broken to be strip form during the compression under 200、250、300 and 350°C. A lot of fine granular second phase particles precipitated with the grain refinement simultaneously in AZ80 alloy deformed in two-phase region with tremendous deformation. There are also fine granular second phase particles precipitated in the alloy deformed in critical region. There are massive β-Mg₁₇Al₁₂ phases precipitated in the alloy deformed under higher temperature such as 350 and 400°C during the water cooling after the compression, the high power observation of which is fine and tightly lamellar microstructure. Compared with coarse reticular β-Mg₁₇Al₁₂ phases in the as-cast microstructure of AZ80 alloy, the morphology of β-Mg₁₇Al12 phases precipitated during the hot compression has obvious improvement.