Rare-earth surface engineering

Extensive work in China since the early 1980s has shown that thermochemical heat treatments and other surface engineering processes are accelerated significantly by incorporating rare-earth elements into the processing medium. With emphasis on its role in carburising, carbonitriding, nitrocarburising and nitriding, this paper reviews the development of the technology and considers the possible mechanisms enhancing mass transfer and kinetics. It also discusses industrial applications which are increasingly taking advantage of the associated operational benefits and property improvements conferred.