| 摘要 |
PROBLEM TO BE SOLVED: To obtain an alloy capable of easily refining the cast structure and crystal grains under ordinary casting conditions by allowing it to have a compsn. essentially consisting of magnesium, contg. specified ratios of boron and manganese and substantially not contg. zirconium and titanium. SOLUTION: The content of boron is >=0.0005 wt.%, and the content of manganese is 0.03 to 1 wt.%. Boron is an element extremly effective for refining the crystals of the magnesium alloy, and the content is desirebly controlled to 0.001 to 0.5 wt.%. Manganese is an element required for refining the crystals of the magnesium alloy in the coexistence with boron, and the content is desirably controlled to 0.05 to 0.8 wt.%. The producing method contains a molten metal adjusting stage in which a crystal grain refining agent contg. at least one kind among metallic boron, a boron-contg. compd. and a boron-contg. alloy and at least one kind among metallic manganese, a manganese-contg. compd. and a manganese-contg. alloy is adjusted into magnesium molten metal and a cooling and solidifying stage in which the molten metal is cooled and solidified. For the magnesium alloy having the fine crystal grains, mechanical properties such as strength, toughness or the like are exceedingly improved.
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