Particulate segregation and mechanical properties in transient liquid phase bonded metal matrix composite material

Abstract

Thefactors determining particulate segregation and joint shear strength in transient liquid phase (TLP) bonded aluminium based metal matrix composite (Mj1C) material are examined in the present paper. Three situations are evaluated during TLP bonding, namely, where the liquid width is unrestrained at the bonding temperature, where the liquid width is maintained constant, and where liquid is continuously expelled from the bondline region during the joining operation. Similar experimental and numerically calculated liquid width values are found during unrestrained liquid width TLP bonding (at the start of the isothermal solidification period). However, the calculated rate constant during isothermal solidification is smaller than in experimental testing. When liquid is expelled from the joint interface during TLP bonding at 853 K, the liquid width attains a constant value of ~55 μm. Although the completion time for isothermal solidification is substantially decreased when liquid is expelled from the joint interface, particulate segregation is still observed in joints produced using 15 and 25 μm thick copper insert metals. Particulate segregation could only be prevented through the use of very thin (<15 μm) copper insert metals. Joint shear strength increases when the thickness of the copper insert metal is decreased and when the applied load increases during liquid expulsion bonding. Higher joint shear strength results from decreased particulate segregation in completed joints.MST/2037