A high strength cast aluminum alloy with accelerated response to heat treatment

Abstract

The invention relates to an improved cast Al alloy designed to provide an accelerated response to heat treatment; specifically, the alloy's response to thermal growth during aging is accelerated, leading to a dimensionally more stable casting. This improvement is achieved by the addition of trace amounts of Sn, In, Ge or Cd to an Al—Si—Cu cast alloy. The improved alloy has particular application for cast Al engine blocks and cylinder heads.

1 . A method of accelerating the heat treatment response time for overaged Al—Si—Cu casting alloys, comprising: 
 adding a metal selected from the group consisting of Sn, Cd, In and Ge to the Al—Si—Cu alloy.  
 
     
     
         2 . A method of accelerating the heat treatment response time for overaged Al—Si—Cu casting alloys, comprising: 
 adding a metal selected from the group consisting of Sn, Cd, In and Ge in an amount between 0.001 and 0.1 wt % to the Al—Si—Cu alloy.  
 
     
     
         3 . The method of  claim 2 , wherein the metal selected is added to the Al—Si—Cu alloy in an amount between 0.01 and 0.1 wt %.  
     
     
         4 . The method of  claim 2 , wherein the metal selected is added to the Al—Si—Cu alloy in an amount between 0.5 and 0.1 wt %.  
     
     
         5 . An improved aluminum casting alloy for having accelerated response to heat treatment, comprising: 
 Si in an amount between 5 and 10 wt %;    Cu in an amount between 1 and 4 wt %; and    a metal selected from the group consisting of Sn, Cd, In and Ge in an amount between 0.0001 and 0.1 wt %.    
     
     
         6 . The improved aluminum casting alloy of  claim 5 , wherein the alloy further comprises: 
 Fe in an amount up to 1.2 wt %;    Mn in an amount up to 0.8 wt %; and    Mg in an amount up to 0.5 wt %.    
     
     
         7 . The improved aluminum casting alloy of  claim 5 , wherein the alloy further comprises: 
 Fe in an amount up to 0.4 wt %;    Mn in an amount between 0.2 and 0.3 wt %; and    Mg in an amount between 0.2 and 0.35 wt %.    
     
     
         8 . An improved aluminum casting alloy for having accelerated response to heat treatment, comprising: 
 Si in an amount between 6.5 and 8 wt %;    Cu in an amount between 3 and 4 wt %; and    a metal selected from the group consisting of Sn, Cd, In and Ge in an amount between 0.001 and 0.1 wt %.    
     
     
         9 . An improved Al—Si—Cu casting alloy for having accelerated response to heat treatment and decreased variability, comprising: 
 Sn in an amount between 0.001 and 0.1 wt %.  
 
     
     
         10 . The improved casting alloy of  claim 9 , further comprising: 
 Sn is in an amount between 0.5 and 0.1 wt %.    
     
     
         11 . The improved casting alloy of  claim 9 , further comprising: 
 Sn in an amount between 0.01 and 0.1 wt %.