Diffusion Bonded Alumina Bodies Using Hydride Nanopowders Interlayers and Structural Investigation of Joint Interface

In this paper، diffusion bonding of dense alumina bodies using hydride nanopowders mixture as the interlayer was investigated. Mixture of aluminum hydride and magnesium alanate was synthesized via mechano chemical activation process. Aluminum and magnesium chloride and lithium alanate were used as precursors. Products of milling process were consisted of nano sized alane and Mg alanates. Alumina bodies were diffusion boned at 300، 350، 400، and 450 ْC، under pressure of 20 Mpa for 30 min dwelling time using custom designed induction hot press. Dissociation of hydride mixture interlayer during diffusion bonding process produced in-situ nanosized alloyed aluminum and aluminum-magnesium intermetallic without any surface oxides. Combination of stoichiometric and non-stoichiometric spinel، oxide، and free metal structures were formed during bonding process. The highest bond strength was about 196 MPa via formation of Mg-Al spinel oxide during bonding at 450ْC.