鉄―銅のろう付現象(第2報)

Abstract

A study has been made on the reaction for dissolution of solid iron in liquid copper-iron solutions of various concentrations and on the migration of molten copper into solid iron. Experiments were carried out; cylindrical samples of base metal iron were immersed in liquid copper-iron alloys with various iron concentrations and then rotated at given revolutions in argon atmosphere in a resistance furnace, and the cylinders of the solid were padded with a small quantity of copper and this copper was melted under vacuum in an induction furnace. The rate of dissolution of solid iron into liquid copper-iron alloy is dependent on the rotational speed, the temperature and the iron concentration. The reaction process was found to be rate-controlled by the diffusion of solute from the iron-copper interface to the liquid and the obtained value of activation energy for dissolution of solid iron in liquid copper-iron alloy was about 14.3 K calf mole. At higher velocities and higher temperatures, however, the transition from pure diffusion control to mixed control is likely to occur with an increasing solute concentration. On the other hand, small amounts of the molten copper migrate through the copper-iron interface into the solid iron and a thin laver of the base metal adjacent to the interface appears to be saturated with the molten copper. The principal mechanism of the transfer of molten copper into the solid iron was shown to be by volume diffusion and by grain boundary diffusion, without liquid metal grain-boundary penetration. The mechanism of the migration was considered variable with the interfacial energy, the grain-size and the temperature. The structure of the solidified iron-copper interface was investigated by means of metallography.