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 resulòting in metal contact melting at 1300°C. Ongoing heating, the in situ formed Ni-B alloys wets, spreads over HfB2 and penetrates the HfB2/Ta capillary interface to form a joint of complex graded structure and good bonding.