This process is based upon the fact that a number of metals can react with carbon monoxide to form carbonyls such as iron carbonyl can be made by passing carbon monoxide over heated iron at 50 – 200 bar pressure. The resulting carbonyl is then decomposed by heating it to a temperature of 200 – 300 ⁰C yielding powder of high purity, however, at higher cost.

These are mechanical methods which produce a relatively coarse powder. Ball mill is employed for brittle materials whereas stamps are used for ductile material.

Granulation Process

This process consists in the formation of an oxide film in individual particles when a bath of metal is stirred in contact with air.

In this method, powders of two or more pure metals are mixed in a ball mill. Under the impact of the hard balls, the powders are repeatedly fractured and welded together by forming alloy under diffusion.

Other methods

The other less commonly used methods to form metallic powder are by (i) precipitation from a chemical solution, (ii) production of fine metals by machining, and (iii) vapour condensation.