Brazing with (NiCoCr)–B–Si amorphous brazing filler metals: Alloys,processing,joint structure,properties,applications

Abstract

This paper is a detailed and updated review of the properties and specifics of METGLAS amorphous brazing foil (MBF) and a review of the positive qualities it has brought to many applications in the last two decades. The major emphasis is to provide practical guidance for intelligent use that will contain, in the first part, a description of these materials in the virgin as cast state. This state has a unique combination of physical properties. The metallurgical background will also be given in this part to the existing range of available chemical compositions and their potential compatibility with various base metals. The amorphous alloy mechanical properties and thermal stability, wettability over various metals and its dependence on the brazing atmosphere and preform preparation will also be described. The second part presents the properties of MBF joints manufactured from various classes of base metals and obtained under optimised brazing conditions for each class of base metals. Particular attention is given to the joint microstructure/properties relationships yielding brazements with high strength, ductility and corrosion and fatigue resistance. Finally, the versatile technical and manufacturing features of MBF are underlined. These features are the driving force behind the rapid expansion of their applications in various industries. Examples of these applications are also given.