Liquid phase diffusion bonding method of metal machine part and such metal machine part

Abstract

A liquid phase diffusion bonding method for a metal machine part superior in the quality of the joint and the productivity enabling the bonding time to be shortened, achieving homogenization of the bonding structure and improving the tensile strength, fatigue strength, and joint quality and reliability. This liquid phase diffusion bonding method of a metal machine part is characterized interposing an amorphous alloy foil for liquid phase diffusion bonding at bevel faces of metal materials, performing primary bonding by melt bonding said amorphous alloy foil and said metal material by resistance welding to form a joint, then performing secondary bonding by liquid phase diffusion bonding by reheating said joint to at least the melting point of said amorphous alloy foil, then holding it there to complete the solidification process of said joint.

1 - 14 . (canceled) 
     
     
         15 . A bonded metal material comprising a first metal material and a second metal material, said bonded metal material being produced by a method comprising:
 (a) melt bonding said first metal material to said second metal material to form a joint, wherein a bonding face of said first metal material forms a V-bevel which contacts a non-beveled bonding face of said second metal material at bevel tip through an amorphous alloy foil for liquid phase diffusion bonding, and wherein said melt bonding comprises (i) passing an electrical current across said first and second metal materials through said bevel tip and said amorphous alloy foil to heat said bevel and said amorphous alloy foil and (ii) applying a pressing stress such that said bevel and said amorphous alloy foil are melted and said bevel is collapsed to form said joint; and   (b) reheating said joint to at least the melting point of said amorphous alloy foil, and allowing an isothermal solidification process of said joint to complete.   
     
     
         16 . The bonded metal material of  claim 15 , wherein the composition of said amorphous alloy foil is Ni or Fe as a base and, as diffusion atoms, one or more of B, P, and C in amounts of 0.1 to 20.0 at % and further V in 0.1 to 10.0 at %. 
     
     
         17 . The bonded metal material of  claim 15 , wherein said joint produced in step (a) comprises an incomplete isothermal solidification structure of an average thickness of not more than 10 μm formed from said amorphous alloy foil. 
     
     
         18 . The bonded metal material of  claim 15 , wherein said step (b) is carried out without applying an external pressure to said metal materials. 
     
     
         19 . The bonded metal material of  claim 15 , wherein said melt bonding is carried out by resistance welding. 
     
     
         20 . A machine part produced by a method comprising
 interposing an amorphous alloy foil for liquid phase diffusion bonding between a first bonding face of a first metal material and a non-beveled bonding face of a second metal material, wherein said first bonding face of said first metal material forms a V-bevel which contacts said non-beveled bonding face of said second metal material at the tip of the bevel through said amorphous alloy foil,   performing primary bonding by melt bonding said amorphous alloy foil and said first and second metal materials to form a joint, wherein said primary bonding comprises (i) passing an electrical current across said first and second metal materials through said contact bevel tip and said amorphous alloy foil to heat said V-bevel and said amorphous alloy foil and (ii) applying a pressing stress such that said V-bevel and said amorphous alloy foil are melted and said V-bevel is collapsed to form said joint,   then performing secondary bonding by reheating said joint to at least the melting point of said amorphous alloy foil, and allowing an isothermal solidification process of said joint to complete.   
     
     
         21 . The machine part of  claim 20 , wherein the composition of said amorphous alloy foil is Ni or Fe as a base and, as diffusion atoms, one or more of B, P, and C in amounts of 0.1 to 20.0 at % and further V in 0.1 to 10.0 at %. 
     
     
         22 . The machine part of  claim 20 , wherein said joint produced in said primary bonding step comprises an incomplete isothermal solidification structure of an average thickness of not more than 10 μm formed from said amorphous alloy foil. 
     
     
         23 . The machine part of  claim 20 , wherein said secondary bonding is carried out without applying an external pressure to said metal materials. 
     
     
         24 . The machine part of  claim 20 , wherein said primary bonding is carried out by resistance welding. 
     
     
         25 . A machine part produced by a method comprising
 interposing an amorphous alloy foil for liquid phase diffusion bonding between metal materials including at bevel faces of at least one metal material of metal materials to be bonded,   performing primary bonding by melt bonding said amorphous alloy foil and said metal materials by resistance welding to form a joint, wherein said resistance welding melts said amorphous metal foil and said bevel faces of said at least one metal material, then performing secondary bonding by liquid phase diffusion bonding by reheating said joint to at least the melting point of said amorphous alloy foil, then holding it there to complete an isothermal solidification process of said joint;   wherein said at least one of said metal materials is a cylindrical metal material and a V-bevel is formed at an end of said cylindrical metal material so that, when bringing the end of said cylindrical metal material into abutment with the surface of another metal material for primary bonding, an inner surface bevel height A and an outer surface bevel height B of said cylindrical metal material with respect to the abutting contact point and a distance C from said abutting contact point to the outer circumference satisfy the following relation (1):
   0.2≦ B/A≦ 1 and  C/t≦ 0.5  (1) 
   where A is an inner surface bevel height of said cylindrical metal material, B is an outer surface bevel height of said cylindrical metal material, C is a distance from an abutting contact point of the cylindrical metal material to the outer circumference, and t is the thickness of the cylindrical metal material; and   wherein a maximum residual height of the bevel ends after said primary bonding is not more than three times the thickness of said amorphous alloy foil.   
     
     
         26 . The machine part of  claim 25 , characterized in that a maximum residual height of the bevel ends after said secondary bonding is not more than 70 μm. 
     
     
         27 . A joint comprising a first metal material, a second metal material, and an amorphous alloy foil, characterized in that said amorphous alloy foil is dissolved in said first and said second metal materials to form a homogenous mixture. 
     
     
         28 . The joint of  claim 27 , wherein said amorphous alloy foil is Ni or Fe based and, as diffusion atoms, one or more of B, P, and C in amounts of 0.1 to 20.0 at % and further V in 0.1 to 10.0 at %. 
     
     
         29 . The joint of  claim 28 , wherein said alloy foil is Ni based, and said joint is homogenous in Ni. 
     
     
         30 . A joint comprising a first metal material, a second metal material, and an amorphous alloy interposed between said first and second metal materials, wherein said amorphous alloy foil forms an incomplete isothermal solidification structure of an average thickness of not more than 10 μm. 
     
     
         31 . The joint of  claim 29 , wherein said incomplete isothermal solidification structure has an average thickness of not more than 3 μm. 
     
     
         32 . A joint assembly for melt bonding and liquid phase diffusion bonding, comprising a first metal material, a second metal material forming a V-bevel, and an amorphous alloy foil, wherein said second metal material contacts said first metal material at the tip of said V-bevel through said amorphous alloy foil.