| 摘要 |
PURPOSE: To improve the durability of an Al alloy casting by pouring the specific alloy into casting molds kept at a specific temp. and cooling the molten metal to solidify after ceramic particles attain a specific concn. in the bottom of the molten metal. CONSTITUTION: SiC particles 1 having an average grain size of 15μm are charged into the Al alloy melt (liquid phase line temp. 600 deg.C) heated up to, for example, 680 deg.C to prepare the Al alloy melt 2 contg. 20vol.% SiC particles 1. The Al alloy melt 2 kept at 680 deg.C is poured into the cavity 6 of the metal molds 5 consisting of upper and lower molds 3, 4 preheated to 650 deg.C in a gaseous nitrogen atmosphere and is held for 60 minutes at 650 deg.C. The SiC particles 1 settle into the molten metal 2 during holding and the SiC particles 1 segregate in the bottom of the Al alloy melt 2. After the concn. of the ceramic (SiC) particles in the bottom of the molten metal 2 attains 10 to 60vol.%, the Al alloy melt is cooled to solidify. As a result, the strength in the boundary part between the section where the ceramic particles are dispersed and the section where these particles are not dispersed is increased.
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