高濃度Al-10, 14%Mg合金における変調構造および規則構造の形成

抄録

The formation of a modulated structure and an ordered structure in concentrated Al-Mg alloys during the low temperature aging was investigated by means of hardness measurements, specific heat measurements at low temperatures and transmission electron microscopy.
Two types of heat absorption due to dissolution of both the modulated and L1₂ ordered structures were observed distinctly in the specific heat curves below a certain critical temperture. Through the precise analysis of heat evolution and absorption, the dependence of these structural changes upon the aging temperature and time was clarified. Both the modulated and L1₂ ordered structures are formed below 353 K, only the L1₂ ordered structure is formed at 358 K and none of them are formed above 363 K in an Al-14%Mg alloy. Consequently, the L1₂ ordered structure is found to be formed in two modes; i.e. one is a continuous formation from the modulated structue and the other the nucleation and growth in the matrix.