モリブデンの拡散接合

抄録

It is generally acknowledged that the ductile joint of molybdenum is difficult to make by fusion welding because of its embrittleness due to recrystallization and grain growth.
The purpose of this investigation is to obtain a ductile joint of pure molybdenum without recrystallization and extreme deformation by diffusion or pressure bonding processes with or without insert metals. The following resuls were obtained.
1. Although the joint of molybdenum without insert metals was accomplished at higher temperature than the recrystallization temperature with 5-10% deformation, the joint made at higher temperature than 1200Δ was brittle due to recrystallization. A transfacial grain growth across the initial bonding interface was observed to occur at 1250Δ for 5 min and such migration of grain boundary was easily obtained relatively at lower temperature compared with that for various metals.
2. It was found that the joint of molybdenum without recrystallization and extreme deformation was accomplished using insert metals such as iron, nickel, copper and silver by electroplating. The remelting temperature of these joints became too higher than the melting points of the insert metals. Although nikel formed an intermetallic compound with molybdenum, nickle insert metal made a stronger joint at low temperature than the others. Copper was also found to be applicable as an insert metal, but it did not alloy with molybdenum.