High Cr content Ni based braze filler metals (BFMs) have become common in many applications because of their low melting points and high corrosion resistance. Still, the brazing community continues to pursue high Fe content BFMs for cost reduction and the reduction of Ni leaching in heat exchanger applications. Fe containing amorphous braze foils with B as the primary melting point depressant have been developed but the resulting high liquidus temperatures have limited commercial adoption. P has become the primary melting point depressant to reduce brazing temperatures in many BFMs today. Intermetallic phases, particularly with P containing alloys, commonly form within the braze layer. Low Cr content in the intermetallic phases can be particularly problematic as they can serve as a site for corrosion initiation. An optimization of the alloy composition and brazing cycle can help to refine phases that are Cr-poor thus enhancing corrosion resistance.
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