Effects of B Addition on Precipitation Behavior of β Phase in Al-Mn-Mg-B Alloys.

In order to investigate the effect of boron on the precipitation behavior of β phase in Al-Mn-Mg-B alloy used as a material for cask baskets, 1.00 © 104 hours aging treatment was carried out focusing on the temperature history in the cask as in the previous report, and the Timetemperature-precipitation diagram and Supersaturation-diffusion length-precipitation diagram were evaluated using the change tendency of the specific resistance obtained. In the Al-Mn-Mg-B alloy, although grain refinement by AlB2 was confirmed, the effect of boron addition on the precipitation rate of β phase was hardly recognized. That is to say, it was confirmed that the grain boundary and the interface between B compounds and matrix phase hardly contributed as nucleation sites of β phase. In conclusion, it is considered that the reduction of the solid solution Mg content in the Al-Mn-Mg-B alloy does not occur even after 60 years if the Mg content is 1.0 mass% as in the Al-Mn-Mg alloy. [ABSTRACT FROM AUTHOR]