Abstract
After a brief review of previous work, and of the nature of the materials involved, the principles are discussed of the method of welding adopted. This is followed by a description of the apparatus and experimental procedure, and their development. The preliminary experimental work has been regarded partly as apparatus proving trials, and partly as a method of observing the behaviour of the materials under the conditions prevailing and likely to prevail in the apparatus. Having obtained this information, the systems considered are dealt with one by one as discreet sections. Each has an introduction, metallographic and discussion sections, but an overall discussion will be found in Chapter XVI. The work shows that in welding the dissimilar rare metals, the nature of the fusion zone is largely dependent on the rate of dissolution of the higher melting point metal, though other factors modify the rate. These factors are compound formation, surface tension of the fluid alloys, and, initially, the heat abstraction tendencies of the parent metals. The shape of the fusion zone contours and the mechanism of their formation are considered in detail, and explanations given for the manner in which they move. Appendices have been added which deal with the estimation of fusion zone compositions and temperature measurement at the weld interface.