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Various metallic interlayers and combinations thereof were investigated for their ability to promote bonding, prevent oxidation and provide compliancy. Within this matrix, beryllium tiles were prepared with different surface finishes to determine the effects of roughness on bond strength. Titanium interlayers were successful in preventing the formation of deleterious Be-Cu intermetallics. Several forms of titanium and copper interlayers were evaluated, including sputter deposition, electron beam evaporation and free standing Cu foils.
Bond strength measurements were quantified using a modified ASTM A263 shear test. Using shear strength as the primary metric for bonding integrity, the most promising combinations of interlayers were investigated while varying the HIP parameters. The results suggest that bonding temperatures of 580 and 560C provide the maximum achievable bond strength, evidenced by fracture in the beryllium tile as opposed to along the joint. Joint strength is significant, even at temperatures as low as 540C
Lastly, the joint microstructures have been analyzed using several different analytic techniques including optical and electron microscopy as well as microprobe and Auger electron spectroscopy to determine diffusion profiles and intermetallic formation. These results will be discussed as they relate to the relative bond strengths that have been measured.