Study of the nano-structured nickel-based brazing filler synthesized by mechanical alloying

摘要

A series of BNi-2 nickel-based brazing fillers were synthesized by mechanical alloying (MA) the appropriate proportion of pure elements in a high-energy ball mill. The results of DTA show an exothermic peak around 700 K, which is presumed to be a metastable phase, for the alloy after 4 tt milling. After 10h milling, the final particle sire of the powder can reach about 20 mum and exhibits a quite even equiaxed shape. The structural evolution with milling time by X-ray diffractometry shows the following transformation: mixture of pure elemental powders --> microcrystalline f.c.c. solid solution --> nanocrystalline f.c.c, solid solution. The crystal size calculated by X-ray diffraction was about 5 nm for the powder after 10h milling. This is in very good agreement with the evidence of nanocrystalline phase obtained by TEM observation. In addition, the evaluation of the brazing properties of the BNi-2 powder synthesized by MA is similar to the gas atomized BNi-2 powder. (C) 2001 Elsevier Science B.V. All rights reserved. References: 12