In the preparation of alloys by sintering metal powders, the alloy is formed by the diffusion of metals into each other. The distribution of metallic powder in space is expressed by means of a triple series; this series is used to obtain the solution of the diffusion equation. The resulting formula gives the concentration of metal as a function of space, time, temperature, and particle size. Sample calculations made for one‐to‐one atomic proportion nickel‐copper alloys are in general agreement with experimental results.