What is the direction of flow for the filler metal and the flux when joining pieces?

When joining pieces using silver brazing, the understanding of the flow direction of both the filler metal and the flux is crucial for achieving a strong bond. The correct answer indicates that the filler metal flows "in" towards the joint, while the flux also flows "out" during the brazing process.

In the context of brazing, the process involves heating the base metals to a temperature that causes the filler metal to melt and flow into the joint by capillary action. As the molten filler metal is introduced to the joint space, it fills the gaps and adheres to the surfaces, thereby creating a solid bond upon cooling.

Simultaneously, the flux, which is applied prior to the brazing process, serves to remove oxides and contaminants on the metal surfaces, facilitating better flow of the filler metal. While the filler metal seeks to fill in the joint area (hence, it flows "in"), the flux performs its cleaning function and can sometimes lead to the expulsion of impurities from the area, flowing outward as the joint is filled.

Understanding this behavior is essential for anyone engaged in silver brazing as it ensures that the filler metal reaches all necessary areas and that the joint integrity is maintained by minimizing the presence of harmful oxides or