Wear-resistant sintered aluminum alloy with high strength and manufacturing method thereof

Abstract

Disclosed is a wear-resistant sintered aluminum alloy with high strength and a manufacturing method thereof. The sintered aluminum alloy contains, by mass: 3.0-10% zinc; 0.5-5.0% magnesium; 0.5-5.0% copper; 0.1-10% hard particles; impurities; and aluminum. The metallographic structure has an aluminum alloy matrix in which the hard particles dispersed; and an intermetallic compound phase being dispersedly precipitated in the aluminum alloy matrix. Using an aluminum powder, a hard particles powder and other powders, a compact is formed and sintered at 580-610 degrees C., then cooled and subjected to heat treatment at a temperature of 460-490 degrees C., including water-quenching and aging at 110-200 degrees C.

1 . A wear-resistant sintered aluminum alloy having high strength, comprising, by mass: 3.0 to 10% zinc; 0.5 to 5.0% magnesium; 0.5 to 5.0% copper; 0.1 to 10% hard particles; an inevitable amount of impurities; and aluminum, 
 and having a metallographic structure comprising: an aluminum alloy matrix in which the hard particles dispersed; and an intermetallic compound phase being dispersedly precipitated in the aluminum alloy matrix.    
     
     
         2 . The wear-resistant sintered aluminum alloy of  claim 1 , wherein the hard particles have a mean particle size of 1 to 100 microns.  
     
     
         3 . The wear-resistant sintered aluminum alloy of  claim 1 , wherein the hard particles are composed of a material having a Vickers hardness of 600 Hv or more and having substantially no reactivity with aluminum.  
     
     
         4 . The wear-resistant sintered aluminum alloy of  claim 1 , wherein the hard particles are composed of at least one material selected from the group consisting of silicon carbide, chromium boride and boron carbide, and the intermetallic compound phase includes at least one selected from the group consisting of MgZn 2 , Al 2 Mg 3 Zn 3  and CuAl 2 .  
     
     
         5 . The wear-resistant sintered aluminum alloy of  claim 1 , further comprising at least one reagent which is selected from the group consisting of tin, bismuth, indium and both of an eutectic compound and a monotactic compound both of which comprise at least one element of tin, bismuth and indium as a main component, and the content of the reagent in the wear-resistant sintered aluminum alloy is 0.01 to 0.5 mass %.  
     
     
         6 . A method of manufacturing a wear-resistant sintered aluminum alloy with high strength, comprising: 
 preparing a raw material powder comprising, by mass: 3.0 to 10% zinc; 0.5 to 5.0% magnesium; 0.5 to 5.0% copper; 0.1 to 10% hard particles; inevitable amount of impurities; and the balance aluminum, by using: an aluminum powder having a particle size of 140 microns or less; a powder for the hard particles, having a particle size of 113 microns or less; and one of combination of simple metal powders, combination of binary alloy powders and combination of a simple metal powder and a binary alloy powder, containing zinc, magnesium and copper and having a particle size of 74 microns or less;    pressing the raw material powder in a die at a compacting pressure of 200 MPa or more to form a compact having a predetermined shape;    sintering the compact in a non-oxidizing atmosphere in such a manner as to heat the compact from 400 degrees C. to a sintering temperature of 590 to 610 degrees C. at an temperature-elevating rate of 10 degrees C./min or more and keep the sintering temperature for 10 minutes or more, before cooling the sintered compact to a room temperature; and    subjecting the compact after the sintering, to heat treatment comprising: heating the compact at a temperature of 460 to 490 degrees C. and water-quenching so as to dissolve a precipitation phase in the aluminum base of the compact to produce solid solution; and keeping the temperature in a range of 110 to 200 degrees C. for 3 to 28 hours to produce a precipitation phase from the solid solution.    
     
     
         7 . The manufacturing method of  claim 6 , further comprising, before the heat treatment, 
 subjecting the sintered compact to cold forging or hot forging, the cold forging comprising pressing the sintered compact at a room temperature with an upsetting ratio being in a range of 3 to 40%, and the hot forging comprising pressing the sintered compact at a temperature of 100 to 450 degrees C. with an upsetting ratio being in a range of 3 to 70%.    
     
     
         8 . The manufacturing method of  claim 6 , wherein the hard particles are composed of a material having a Vickers hardness of 600 H v  or more and having substantially no reactivity with aluminum.  
     
     
         9 . The manufacturing method of  claim 6 , wherein the hard particles are composed of at least one material selected from the group consisting of silicon carbide, chromium boride and boron carbide.  
     
     
         10 . The manufacturing method of  claim 6 , further comprising, before the pressing, 
 adding to the raw material powder at least one reagent which is selected from the group consisting of tin, bismuth, indium and both of an eutectic compound and a monotactic compound both of which comprise at least one element of tin, bismuth and indium as a main component, at the content of the reagent being 0.01 to 0.5 mass % in the total of the reagent and the raw material powder.    
     
     
         11 . The manufacturing method of  claim 6 , wherein the non-oxidizing atmosphere at the sintering is a nitrogen gas atmosphere having a dew point of −40 degrees C. or less.  
     
     
         12 . A method of manufacturing a wear-resistant sintered aluminum alloy with high strength, comprising: 
 preparing a raw material powder comprising, by mass: 3.0 to 10% zinc; 0.5 to 5.0% magnesium; 0.5 to 5.0% copper; 0.1 to 10% hard particles; inevitable amount of impurities; and the balance aluminum, by using: a simple aluminum powder of at least 15 mass % of the raw material powder; an aluminum alloy powder containing the whole of zinc which the raw material powder comprises; and a powder for the hard particles at 0.1 to 10 mass % of the raw material powder;    pressing the raw material powder in a die at a compacting pressure of 200 MPa or more to form a compact having a predetermined shape;    sintering the compact in a non-oxidizing atmosphere at a sintering temperature of 580 to 610 degrees C. for 10 minutes or more, before cooling the sintered compact to a room temperature; and    subjecting the compact after the sintering, to heat treatment comprising: heating the compact at a temperature of 460 to 490 degrees C. and water-quenching so as to dissolve a precipitation phase in the aluminum base of the compact to produce solid solution; and keeping the temperature in a range of 110 to 200 degrees C. for 2 to 28 hours to produce a precipitation phase from the solid solution.    
     
     
         13 . The manufacturing method of  claim 12 , further comprising, before the heat treatment, subjecting the sintered compact to cold forging or hot forging, the cold forging comprising pressing the sintered compact at a room temperature with an upsetting ratio being in a range of 3 to 40%, and the hot forging comprising pressing the sintered compact at a temperature of 100 to 450 degrees C. with an upsetting ratio being in a range of 3 to 70%.  
     
     
         14 . The manufacturing method of  claim 12 , wherein the aluminum alloy powder has a composition comprising 10 to 30 mass % of zinc, an inevitable amount of impurities and the balance aluminum.  
     
     
         15 . The manufacturing method of  claim 12 , wherein, at the preparing, the aluminum alloy powder contains 10 mass % or less of copper.  
     
     
         16 . The manufacturing method of  claim 12 , wherein the hard particles are composed of a material having a Vickers hardness of 1000 H v  or more and having substantially no reactivity with aluminum.  
     
     
         17 . The manufacturing method of  claim 12 , wherein the hard particles are composed of at least one material selected from the group consisting of silicon carbide, chromium boride and boron carbide.  
     
     
         18 . The manufacturing method of  claim 12 , further comprising, before the pressing, 
 adding to the raw material powder at least one reagent which is selected from the group consisting of tin, bismuth, indium and both of an eutectic compound and a monotactic compound both of which comprise at least one element of tin, bismuth and indium as a main component, at the content of the reagent being 0.01 to 0.5 mass % in the total of the reagent and the raw material powder.    
     
     
         19 . The manufacturing method of  claim 12 , wherein, at the preparing, the aluminum powder and the aluminum alloy powder have a particle size of 140 microns or less, a powder for the hard particles has a particle size of 113 microns or less, and the preparing further comprises using at least one powder having a particle size of 74 microns or less is used for magnesium and copper.  
     
     
         20 . The manufacturing method of  claim 12 , wherein the non-oxidizing atmosphere at the sintering is a nitrogen gas atmosphere having a dew point of −40 degrees C. or less.