WETTING and JOINING of HfB₂ and Ta with Ni

The wetting behavior of Ni on a HfB₂/Ta assembly was examined in vacuum using dense HfB₂ (99.5% purity) produced, without sintering aids, by HP-HT at 7 GPa. The real-time imaging by a high resolution digital camera and precise temperature control demonstrated solid-state Ni/HfB₂ interaction resulting in metal contact melting at ~1300ºC. Ongoing heating, the in situ formed Ni-B alloy wets, spreads over HfB₂ and penetrates the HfB₂/Ta capillary interface to form a joint of complex graded structure and good bonding.

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