Contamination in wet-ball milling

The top-down approach of mechanical ball milling/alloying is the most commonly adopted route towards materials development. It is however surprising that despite the large impact that it has, process induced contamination (particularly from process control agents (PCAs)), remains less studied and often ignored. In this article, a theory that explains the cause of PCA-induced contamination is postulated. An attempt is then made through reviewing the literature to reason why there is ignorance. Influence of contamination on material's properties is then reviewed; revealing the dubious behaviour of contaminants. No first-hand experimental data are presented. The article is written with the interest and objective to create awareness on contamination, which remains highly under appreciated.