Hardened alloy composite materials and method of manufacture

Abstract

A hardened alloy composite material comprising an alloy matrix and reinforcing particles dispersed in the alloy matrix, the reinforcing particles having a shell and core structure, wherein the shell and the core have different chemical compositions, and wherein the reinforcing particles are formed by a MAX phase compound and/or a MAB phase compound.

1 . A hardened alloy composite material comprising:
 an alloy matrix; and   reinforcing particles dispersed in the alloy matrix, the reinforcing particles having a shell and core structure, wherein the shell and the core have different chemical compositions, wherein the reinforcing particles are formed by a MAX phase compound and/or a MAB phase compound.   
     
     
         2 . The hardened alloy composite material of  claim 1  and having a porosity equal to or greater than 14 percent. 
     
     
         3 . The hardened alloy composite material of  claim 2 , wherein a hardness of the hardened alloy composite is greater than 6,000 MPa as determined by the Vickers hardness test. 
     
     
         4 . The hardened alloy composite material of  claim 1 , wherein a constituent of the at least one of a MAX phase and a MAB phase alloys with iron in the alloy matrix to form a shell around remaining constituents of the MAX phase and/or a MAB phase. 
     
     
         5 . The hardened alloy composite material of  claim 4 , wherein the alloy matrix is a bearing steel. 
     
     
         6 . The hardened alloy composite material of  claim 5 , wherein the MAX phase compound has the chemical formula: M n+1 AX n , wherein M is at least one early transition metal selected from groups IIIB, IVB, VB, and VIB, A is at least one element selected from groups IIIA, IVA, VA, VIA, and VIIA, X is one or both of carbon and nitrogen, and n is an integer between 1 and 3, and wherein A forms the shell. 
     
     
         7 . The hardened alloy composite of  claim 6 , wherein the MAX phase compound is Cr 2 AlC. 
     
     
         8 . The hardened alloy composite material of  claim 1  being fully dense and having hardness of the hardened alloy composite is greater than 8,000 MPa as determined by the Vickers. 
     
     
         9 . The hardened alloy composite material of  claim 1 , wherein the MAX phase or MAB phase compound forms a deoxidizing agent that absorbs excess oxygen in the alloy matrix. 
     
     
         10 . A method of manufacturing a hardened alloy composite material, the method comprising:
 combining an alloy powder and a reinforcing powder to form a powder mixture, wherein the reinforcing powder comprises a MAX phase compound and/or a MAB phase compound;   consolidating the powder mixture by cold pressing to form a consolidated powder mixture;   densifying the consolidated powder mixture by sintering to form a densified material; and   hardening the densified material by application of a quenching heat treatment to form the hardened alloy composite material, wherein a microstructure of the hardened alloy composite comprises reinforcing particles interspersed in an alloy matrix, the reinforcing particles having a shell and core structure, wherein the shell and the core have different chemical compositions.   
     
     
         11 . The method of  claim 10 , wherein the alloy powder is a bearing steel. 
     
     
         12 . The method of  claim 11 , wherein the powder mixture comprises at least 5% by volume the MAX phase compound or the MAB phase compound and wherein the MAX phase compound has the chemical formula: M n+1 AX n , wherein M is at least one early transition metal selected from groups IIIB, IVB, VB, and VIB, A is at least one element selected from groups IIIA, IVA, VA, VIA, and VIIA, X is one or both of carbon and nitrogen, and n is an integer between 1 and 3, and wherein A forms the shell. 
     
     
         13 . The method of  claim 12 , wherein the reinforcing powder comprises Cr 2 AlC and wherein the core comprises chromium carbide. 
     
     
         14 . The method of  claim 10 , wherein the microstructure of the hardened alloy composite material further comprises martensite. 
     
     
         15 . The method of  claim 10 , wherein each of the alloy powder and the reinforcing powder have a particle size equal to or less than approximately 40 micrometers. 
     
     
         16 . The method of  claim 10 , wherein densifying the consolidated powder mixture comprises sintering in an unpressurized furnace, the resulting densified material having a porosity equal to or greater than 14 percent. 
     
     
         17 . The method of  claim 10 , wherein a hardness of the hardened alloy composite is greater than 6,000 MPa as determined by the Vickers hardness test. 
     
     
         18 . The method of  claim 10 , wherein densifying the consolidated powder mixture comprises hot isostatic pressing. 
     
     
         19 . The method of  claim 18 , wherein a hardness of the hardened alloy composite is greater than 8,000 MPa as determined by the Vickers hardness test. 
     
     
         20 . A hardened alloy composite material comprising:
 an alloy matrix;   first reinforcing particles dispersed in the alloy matrix, the first reinforcing particles formed by a MAX phase compound and/or a MAB phase compound and having a shell and core structure, wherein the shell and the core have different chemical compositions; and   second reinforcing particles in the alloy matrix, the second reinforcing particles formed by an oxide of the A element of the at least one MAX or MAB phase compound.