Fresh water dissolvable aluminum alloy

Abstract

A dissolvable aluminum alloy can be used for components of a downhole tool in hydraulic fracturing operations with low salinity fluid at low temperatures, including fresh water. The dissolvable aluminum alloy can be dissolved completely and controlled at a dissolving rate compatible with hydraulic fracturing operations. The alloy comprises aluminum having grain boundaries, magnesium at 8.25-12% by weight, gallium at 2.5-4% by weight, and indium at 2-4% by weight. At least portions of magnesium, gallium, and indium are located in the grain boundaries. There are secondary phase particles, including Al—Mg Beta, Mg2Si, Mg and Al—Ga Gamma phases at the grain boundaries.

We claim: 
     
         1 . A dissolvable alloy for components of a downhole tool, comprising:
 aluminum having grain boundaries;   magnesium at 8.25-12% by weight;   gallium at 2.5-4% by weight; and   indium at 2-4% by weight,   wherein at least portions of magnesium, gallium, and indium are located in said grain boundaries so as to be dissolvable a salinity between 0-3% by weight at temperatures between 50-60° C. with a dissolving rate less than 100 mg/cm2/hr.   
     
     
         2 . The dissolvable alloy of  claim 1 , wherein said aluminum, said magnesium, and said gallium are comprised of secondary phases, said secondary phases being Al—Mg Beta phases, Mg phases, and Al—Ga Gamma phases. 
     
     
         3 . The dissolvable alloy of  claim 2 , wherein at least portions of said secondary phases are located in said grain boundaries. 
     
     
         4 . The dissolvable alloy of  claim 2 , wherein said secondary phases are comprised of 10 Mo. % Al—Mg Beta phases, 0.85 Mol. % Mg phases, and 0.2 Mol. % Al—Ga Gamma phases. 
     
     
         5 . The dissolvable alloy of  claim 1 , further comprising: silicon at 0.2-0.4% by weight. 
     
     
         6 . The dissolvable alloy of  claim 5 , wherein said aluminum, said magnesium, said gallium, and said silicon are comprised of secondary phases, said secondary phases being Al—Mg Beta phases, Mg2Si phases, Mg phases, and Al—Ga Gamma phases. 
     
     
         7 . The dissolvable alloy of  claim 5 , wherein said secondary phases are comprised of 10 Mo. % Al—Mg Beta phases, 2.3 Mol. % Mg2Si, 0.85 Mol. % Mg phases, and 0.2 Mol. % Al—Ga Gamma phases. 
     
     
         8 . The dissolvable alloy of  claim 1 , further comprising: tin at 1.0-3.0% by weight. 
     
     
         9 . The dissolvable alloy of  claim 1 , further comprising: manganese at less than 0.2% by weight. 
     
     
         10 . The dissolvable alloy of  claim 1 , wherein magnesium is 8.5% by weight, wherein gallium is 5.0% by weight, and wherein indium is 3.0% by weight. 
     
     
         11 . The dissolvable alloy of  claim 1 , wherein the dissolving rate is 20-40 mg/cm2/hr in deionized water at 50° C. 
     
     
         12 . The dissolvable alloy of  claim 1 , wherein the dissolving rate is 35-55 mg/cm2/hr in 3% KCI at 50° C. 
     
     
         13 . The dissolvable alloy of  claim 1 , wherein the dissolving rate is 60-90 mg/cm2/hr in 1% KCI at 60° C. 
     
     
         14 . The dissolvable alloy of  claim 1 , wherein the dissolving rate is 240-400 mg/cm2/hr in 1% KCI at 93° C.