STRESS IN NI-MO ALLOYS ELECTRODEPOSITED FROM AMMONIACAL CITRATE SOLUTION

To understand the relation between the internal stress and molybdenum content in electrodeposited Ni-Mo alloys, measurement of the stress wa s carried out using both strain gauge and x-ray diffraction methods. T he alloy was electrodeposited from an ammoniacal citrate bath containi ng nickel sulfate and sodium molybdate. Molybdenum content in the allo y increased with an increase in molybdate ion concentration and a decr ease in cathodic current density. The internal stress measured by the strain gauge method decreased with an increase in molybdenum content a nd cathodic current density. On the other hand, the stress measured by the X-ray diffraction method only slightly changed, but both crystall ite size and crystallinity decreased with an increase in molybdenum co ntent. These data suggest that the internal stress in the alloy is dep endent upon the condition of crystallite coalescence.