| 摘要 |
PROBLEM TO BE SOLVED: To provide an aluminum alloy for a magnetic disk and a substrate for a magnetic disk in which recycling properties are secured, and further, desired smoothness can be obtained while maintaing its mechanical properties equal to those of the conventional aluminum alloy substrate for a magnetic disk by optimizing the amounts of Fe, Si and Ni to be added and influencing the formation of intermetallic compounds and consequently controlling the sizes and numbers of intermetallic compounds and crystallized products. SOLUTION: The aluminum alloy substrate for a magnetic disk has a composition containing, by mass, 0.01 to 0.1% Cu, 3.0 to 6.0% Mg, 0.02 to 0.1% Cr, 0.04 to 0.7% Zn and 0.001 to 0.02% Ni, and the balance Al with impurities. Among the impurities, the contents of Fe and Si are respectively controlled to <=0.02%, and <=0.02%, and the content of the other inevitable elements is individually controlled to <=0.01% and further the content of Fe +Ni is <=0.03%. The maximum size of Al-Fe based intermetallic compounds is <=6μm, and the maximum size of Mg-Si based intermetallic compounds is <=3μm.
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