Manufacture of shape memory alloy cellular materials and structures by transient-liquid reactive joining

Abstract

This invention discloses a method, using pure niobium as a transient liquid reactive braze material, for fabrication of cellular or honeycomb structures, wire space-frames or other sparse builtup structures or discrete articles using Nitinol (near equiatomic titanium-nickel alloy) and related shape-memory and superelastic alloys. Nitinol shape memory alloys (SMAs), acquired in a form such as corrugated sheet, discrete tubes or wires, may be joined together using the newly discovered technique. Pure niobium when brought into contact with Nitinol at elevated temperature, liquefies at temperatures below the melting point and flows readily into capillary spaces between the elements to be joined, thus forming a strong joint. A series of diagrams of the interface at various stages of brazing is illustrated by FIG.