Friction stir-welding using a PCBN-based tool containing superalloys

摘要

A polycrystalline cubic boron nitride (pCBN) composite material comprising (by volume): 70-95 % cubic boron nitride particles and 30-5 % binder matrix material in which the cBN particles are dispersed. The binder matrix material comprises one or more superalloys (e.g. TZM). The binder can comprise (by weight): 70-80 % tungsten, 15-30 % rhenium and 0.1-15 % superalloy. The binder can further comprise aluminium is a form other than oxide. The material can be used to make a friction stir welding tool 14, the material can be made by mixing particles of cBN with powder comprising at least one superalloy and optionally aluminium powder, compacting the mixture, outgassing under a vacuum at a temperature in the range 800-1100 0C and sintering at a temperature in the range 1300-1600 0C at a pressure of at least 3.5 GPa. Figure 7 shows a friction stir welding tool 14 joined to a backing element 102 made of Inconel 718.