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Effects of Heat Treatment on Hardness of Nanocrystalline Ni-W Electrodeposits

2006; Trans Tech Publications; Volume: 510-511; Linguagem: Inglês

10.4028/www.scientific.net/msf.510-511.1126

1662-9760

Woon Suk Hwang, Jeong Ja Lee,

Advanced materials and composites

The effects of W content and heat treatment on the hardness of Ni-W alloy deposits were investigated by XRD and Vickers microhardness test. The surface characteristics were also evaluated with respect to the surface roughness and glossiness. With increasing W content, the surface glossiness increased, but the surface roughness decreased. And the amorphous Ni-49wt.% W and 58wt.%W deposits had higher glossiness and lower surface roughness than crystalline Ni-W deposits. The hardness of Ni-W alloy deposits increased with increasing W content because of the solid solution hardening and grain size refinement. As the heat treatment temperature was increased, the hardness increased to reach the maximum of 1300VHN at 600°C for Ni-58wt.%W deposit. The precipitation of intermetallic compounds such as Ni 4 W and NiW seemed to contribute to the increase of hardness. However, the hardness decreased at higher temperature than 600°C owing to the precipitation of pure W, which was supersaturated in Ni matrix.