What is the recommended state for the filler metal to ensure proper flow between solids?

The recommended state for the filler metal to ensure proper flow between solids is liquid. When braze joints are created, the filler metal must be in a molten state to effectively flow and fill gaps between the base materials. This liquid state allows the filler metal to capillary action, which draws it into tight spaces and ensures that it bonds well with both pieces being joined.

During the brazing process, the base metals are heated to a temperature that is above the melting point of the filler metal, allowing it to flow easily into the joint. Once the molten filler metal is in place and the heat is removed, it solidifies, creating a strong bond. This process is critical because a solid or powdered state would not allow for the necessary mobility to fill the joint effectively, leading to weak or incomplete joints. Thus, achieving a liquid state is essential for successful brazing operations.