The growing use of molybdenum-copper in fields in which up to now only tung- sten-copper electric contact composite materials have been employed calls for research into ways of improving the processes involved in their manufacture. Now in the production of

In the detemnination of the solubility of molybdenum in a copper--nickel melt sheet molybdenum specimens were 4m~,ersed in the melt, held in it at a constant temperature until saturation was reached, and then extracted from it. During the isothermal holding the temperature was maintained constant with accuracy to within 176 During the impregnation of the melt and after the extraction of the molybdenum specimens melt samples were collected and analyzed colorimetrically, by the thiocyanate method [2], for molybdenum. The extracted molybdenum specimens were treated with a special solvent based on nitric and phosphoric acids to rid them of solidified alloy layers. During the time necessary for removing the alloy layers in this solvent (~<15 h) molybdenum specimens of 10-cm 2 surface area experienced a weight change of not more than 3.10 -4 g. The amount of dissolved molybdenum was determined as the difference between the weights of the specimens before and after the experiment. In such solubility studies based on weight loss determinations intergranular penetration and diffusion of the alloy melt components into molybdenum specimens could introduce a considerable error. In this work, however, no :intergranular penetrationof the copper-nickel melt into the molybdenum specimens was observed (Fig. i). Systematic error in the solubility determinations due to diffusional penetration of copper and nickel into the molybdenum specimens decreased with rise in nickel concentration in the melt, and did not exceed 4%. Errors linked with incomplete impregnation of such a melt with molybdenum and those caused by the recrystallization molybdenum through the melt are difficult to assess. They can be minimized, however, by choosing an optimum duration of melt impregnation and decreasing temperature gradients and fluctuations during the isothermal holding. When a melt possesses a large solubility for molybdenum, these errors become dominant. When the solubility of molybdenum in a melt is small, errors associated with the specimen weight determinations and with the solution of nickel in the molybdenum predominate.