Heat-resistant, high-toughness aluminum alloy, method of manufacturing the same, and engine parts

Abstract

This invention provides a heat-resistant, high-toughness aluminum alloy which has a good balance between strength and ductility at a temperature from room temperature to around 300 degrees C. and has a high fracture toughness, a method of manufacturing the same, and engine parts. The heat-resistant, high-toughness aluminum alloy of this invention contains 10 to 16 mass. % of silicon, 1 to 3 mass % of iron, 1 to 2 mass % of nickel, 0.5 to 2 mass % in total of one or more selected from the group consisting of titanium, zirconium, chromium and vanadium, 0.6 to 3 mass % of copper, and 0.2 to 2 mass % of magnesium, the balance being essentially aluminum, and is obtained by densifying aluminum alloy powder prepared by gas atomizing. The silicon has an average grain diameter of 4 μm or less.

1 . A heat-resistant, high-toughness aluminum alloy comprising not less than 10 mass % and not more than 16 mass % of silicon, not less than 1 mass % and not more than 3 mass % of iron, not less than 1 mass % and not more than 2 mass % of nickel, not less than 0.5 mass % and not more than 2 mass % in total of one or more selected from the group consisting of titanium, zirconium, chromium and vanadium, not less than 0.6 mass % and not more than 3 mass % of copper, and not less than 0.2 mass % and not more than 2 mass % of magnesium, the balance being essentially aluminum, said alloy being obtained by densifying aluminum alloy powder prepared by gas atomizing, said silicon having an average grain diameter of not more than 4 μm.  
   
   
       2 . The heat-resistant, high-toughness aluminum alloy of  claim 1  which contains titanium by not less than 0.5 mass % and not more than 2 mass %.  
   
   
       3 . The heat-resistant, high-toughness aluminum alloy of  claim 1  or  2  having a density of 2.8 Mg/m 3  or less.  
   
   
       4 . An engine part manufactured by subjecting the heat-resistant, high-toughness aluminum alloy of any of  claims 1  to  3  to hot plastic working.  
   
   
       5 . The engine part of  claim 4  which is a piston.  
   
   
       6 . A method of manufacturing a heat-resistant, high-toughness aluminum alloy comprising: 
 preparing aluminum alloy powder by gas atomizing, said aluminum alloy powder comprising not less than 10 mass % and not more than 16 mass % of silicon, not less than 1 mass % and not more than 3 mass % of iron, not less than 1 mass % and not more than 2 mass % of nickel, not less than 0.5 mass % and not more than 2 mass % in total of one or more selected from the group consisting of titanium, zirconium, chromium and vanadium, not less than 0.6 mass % and not more than 3 mass % of copper, and not less than 0.2 mass % and not more than 2 mass % of magnesium, the balance being essentially aluminum;    subjecting said aluminum alloy powder to cold forming to obtain a preform;    heating said preform to a temperature range of not less than 400 degrees C. and not more than 510 degrees C. and holding said preform in said temperature range for 5 hours or less; and    subjecting said preform to hot plastic working to densify said preform, thereby obtaining a dense body as said heat-resistant, high-toughness aluminum alloy;    the silicon in said aluminum alloy having an average grain diameter of 4 μm or less.    
   
   
       7 . A method of manufacturing a heat-resistant, high-toughness aluminum alloy comprising: 
 preparing aluminum alloy powder by gas atomizing, said aluminum alloy powder comprising not less than 10 mass % and not more than 16 mass % of silicon, not less than 1 mass % and not more than 3 mass % of iron, not less than 1 mass % and not more than 2 mass % of nickel, not less than 0.5 mass % and not more than 2 mass % in total of one or more selected from the group consisting of titanium, zirconium, chromium and vanadium, not less than 0.6 mass % and not more than 3 mass % of copper, and not less than 0.2 mass % and not more than 2 mass % of magnesium, the balance being essentially aluminum;    subjecting said aluminum alloy powder to cold forming to obtain a preform;    heating said preform to a temperature range of 400 degrees C. to 510 degrees C. and holding said preform in said temperature range for 5 hours or less;    subjecting said preform to hot plastic working to densify said preform, thereby obtaining a dense body; and    subjecting said dense body to hot plastic working by heating to a temperature not higher than the heating temperature of said preform, thereby manufacturing said aluminum alloy;    the silicon in said aluminum alloy having an average grain diameter of 4 μm or less.    
   
   
       8 . The method of  claim 6  or  7  wherein the step of subjecting said preform to hot plastic working includes extruding with an extrusion ratio of 6 or more.