Electrochemical Deposition of Tungsten and Molybdenum with Iron Group Metals - 5. Properties of Alloy Coatings of Tungsten and Molybdenum with Iron Metals.

Tests were carried out to show the effect of the composition and layer thickness on the properties of tungsten-cobalt, molybdenum-cobalt, and tungsten-molybdenum-cobalt coatings. Among other things, the formation of the crack network was investigated, and it was established that it forms when the layer thickness is in excess of 2 mu m and that it greatly depends on the composition of the alloy. An X-ray analysis revealed the presence of a two-phase structure in tungsten alloys: tungsten in the solid solution as W//6Co//7 and molybdenum as Co//3Mo and Co//3Mo//3X, where X equals C or O. Tests of internal stresses established the presence of tensile stresses in tungsten alloy coatings and compressive stresses in molybdenum alloy coatings. It was also found that the ternary alloys can be deposited practically stress-free.