Metal powder for powder metallurgy, compound, granulated powder, and sintered body

Abstract

A metal powder comprising particles, which contain Fe, Cr, Si and C, and in which when one element selected from the group consisting of Ti, V, Y, Zr, Nb, Hf, and Ta is defined as a first element, and one element selected from the group consisting of Ti, V, Y, Zr, Nb, Hf, and Ta, and having a higher group number in the periodic table than that of the first element or having the same group number in the periodic table as that of the first element and a higher period number in the periodic table than that of the first element is defined as a second element, the first element is contained in a proportion of 0.01% by mass or more and 0.5% by mass or less, and the second element is contained in a proportion of 0.01% by mass or more and 0.5% by mass or less.

What is claimed is: 
     
         1 . A metal powder for powder metallurgy, comprising particles, which contain
 Fe as a principal component,   Cr in a proportion of 0.2% by mass or more and 35% by mass or less,   Si in a proportion of 0.2% by mass or more and 3% by mass or less, and   C in a proportion of 0.005% by mass or more and 2% by mass or less, and in which   when one element selected from the group consisting of Ti, V, Y, Zr, Nb, Hf, and Ta is defined as a first element, and one element selected from the group consisting of Ti, V, Y, Zr, Nb, Hf, and Ta, and having a higher group number in the periodic table than that of the first element or having the same group number in the periodic table as that of the first element and a higher period number in the periodic table than that of the first element is defined as a second element,   the first element is contained in a proportion of 0.01% by mass or more and 0.5% by mass or less, and   the second element is contained in a proportion of 0.01% by mass or more and 0.5% by mass or less, wherein   the content of Cr on the surface of each particle is 0.2% by atom or more and 15% by atom or less and is 70% or more and 170% or less the content of Cr at a depth of 60 nm from the surface of the particle.   
     
     
         2 . The metal powder for powder metallurgy according to  claim 1 , wherein the content of Si on the surface of each particle is 155% or more and 800% or less the content of Si at a depth of 60 nm from the surface of the particle. 
     
     
         3 . The metal powder for powder metallurgy according to  claim 1 , wherein the ratio of the content of O to the content of Si on the surface of each particle is 0.05 or more and 0.4 or less. 
     
     
         4 . The metal powder for powder metallurgy according to  claim 1 , wherein the content of Cr on the surface of each particle is lower than the content of Cr in the whole particle. 
     
     
         5 . The metal powder for powder metallurgy according to  claim 1 , wherein the ratio (X1/X2) of a value (X1) obtained by dividing the content (E1) of the first element by the mass number of the first element to a value (X2) obtained by dividing the content (E2) of the second element by the mass number of the second element is 0.3 or more and 3 or less. 
     
     
         6 . The metal powder for powder metallurgy according to  claim 1 , wherein the sum of the content of the first element and the content of the second element is 0.05% by mass or more and 0.8% by mass or less. 
     
     
         7 . The metal powder for powder metallurgy according to  claim 1 , wherein the metal powder has an average particle diameter of 0.5 μm or more and 30 μm or less. 
     
     
         8 . A compound, comprising the metal powder for powder metallurgy according to  claim 1  and a binder which binds the particles of the metal powder for powder metallurgy to one another. 
     
     
         9 . A compound, comprising the metal powder for powder metallurgy according to  claim 2  and a binder which binds the particles of the metal powder for powder metallurgy to one another. 
     
     
         10 . A compound, comprising the metal powder for powder metallurgy according to  claim 3  and a binder which binds the particles of the metal powder for powder metallurgy to one another. 
     
     
         11 . A compound, comprising the metal powder for powder metallurgy according to  claim 4  and a binder which binds the particles of the metal powder for powder metallurgy to one another. 
     
     
         12 . A granulated powder, wherein the granulated powder is obtained by granulating the metal powder for powder metallurgy according to  claim 1 . 
     
     
         13 . A granulated powder, wherein the granulated powder is obtained by granulating the metal powder for powder metallurgy according to  claim 2 . 
     
     
         14 . A granulated powder, wherein the granulated powder is obtained by granulating the metal powder for powder metallurgy according to  claim 3 . 
     
     
         15 . A granulated powder, wherein the granulated powder is obtained by granulating the metal powder for powder metallurgy according to  claim 4 . 
     
     
         16 . A sintered body, wherein the sintered body is produced by sintering the metal powder for powder metallurgy according to  claim 1 . 
     
     
         17 . A sintered body, wherein the sintered body is produced by sintering the metal powder for powder metallurgy according to  claim 2 . 
     
     
         18 . A sintered body, wherein the sintered body is produced by sintering the metal powder for powder metallurgy according to  claim 3 . 
     
     
         19 . A sintered body, wherein the sintered body is produced by sintering the metal powder for powder metallurgy according to  claim 4 .