ほう酸アルミニウムウィスカ強化Al–Cu–Mg合金の機械的性質に及ぼすMg量の影響

The influence of the variation of magnesium content on mechanical properties was investigated on aluminum-borate whisker reinforced Al–Cu–Mg alloys, which were fabricated by a squeeze casting process. Tensile strength of the composites decreased with the increased magnesium content in the matrix. However, with the magnesium content above 2%, tensile strength increased and showed a maximum at 3%. In case of the magnesium content below 2%, the whiskers were degraded by the polygonal reaction products which formed on the whisker surfaces by the reaction with magnesium in the matrix. Moreover, the age-hardening of the composites was small due to the consumption of solute magnesium in the matrix. While, in the case of the magnesium content above 2%, a part of magnesium in the matrix contributed to the precipitation, and the larger age-hardening took place in the composites. In addition, the whisker surfaces were covered with the reaction layer. Therefore, irregularity of the whisker surfaces became smaller than that for the magnesium content below 2%, and the decrease of the tensile strength by the whisker degradation also decreased.