ALUMINUM ALLOY FOR MAGNETIC DISK BASE PLATE HAVING GOOD NI-P PLATING PROPERTY

摘要

PURPOSE:To offer an aluminum alloy for a magnetic disk base plate, excellent in mirror finishing properties, corrosion resistance or the like by constituting it of Al as main components and specified content of Mg, Cu, Si, Fe, Ga, Zn and Be and regulating the distribution of intermetallic compounds of coarse grains to specified one. CONSTITUTION:This aluminum alloy for a magnetic disk base plate is constituted of a compsn. contg., by mass %, 3 to 5% Mg, 0.01 to 0.2% Cu, 0.02 to 0.1% Si, 0.03 to 0.1% Fe, 50 to 400ppm Ga, 0.5 to 100ppm Be, 0.05% Zn and the balance Al with inevitable impurities. Furthermore, the distribution of intermetallic compounds of =7mum is regulated to =10 pieces/mm2. In this aluminum alloy, an extremely uniform and fine NiP plating layer can be formed, so that it is suitably used as the one for a magnetic disk base plate.