Method of forming dual metal structures

摘要

A method for forming a structure having an inner portion of a first metal and an outer portion of a second metal involves employing a spray forming processing. The beginning stages of the spray forming is performed with a first metal (22) in a dispensing crucible (24) which supplies a stream of the first metal to an atomization zone (14) where the stream is broken up into many droplets which are driven by an atomizing gas onto a receiving surface (10). The second stage of the processing (Fig. 2) involves adding small quantities of a second metal (28) to the dispensing crucible before the first metal is completely drained therefrom to permit a blend of the two metals to be formed on the preform between an inner and an outer portion thereof. The third phase of the method is the addition of the second metal to the dispensing crucible so that the latter stages of the spray forming is performed with the second metal and accordingly that the outer portions of the preform are formed of the second metal. A desirable good metallurgical bond is formed between the inner and the outer portions of the preform. The first and second metals may both be nickel base superalloys.