A process and apparatus for forming wires, such as wires used as feedstock in welding, brazing, and coating deposition processes. The process and apparatus generally entail feeding through a passage a quantity of powder particles of a size and composition that render the particles susceptible to microwave radiation. As the particles travel through the passage, the particles within the passage are subjected to microwave radiation so that the particles couple with the microwave radiation and are sufficiently heated to melt at least a radially outermost quantity of particles within the passage. The particles are then cooled so that the radially outermost quantity of particles solidifies to yield a wire having a consolidated outermost region surrounding an interior region of the wire.