HARDENNING AND SOFTENNING EFFECTS OF Fe-Cu NANOCRYSTALLINE SUPERSATURATED SOLID SOLUTION FORMED BY MECHANICAL ALLOYING

In present work nanocrystalline supersaturated solid solutions (NSSS) with bcc and fcc structures were prepared in Fe-rich and Curich compostion of immiscible Fe-Cu system respectively by mechanical alloying. The effects of grain size and composition on the hardness of Fe-Cu NSSS have been studied by X-ray diffraction and Vickers hardness measurement. It has been found that the hardness of NSSS formed in Cu-rich composition increases with the increase of Fe, its solute atom content. On the contrary, the hardness of NSSS formed in Fe-rich composition decreases with the increase in Cu content.The hardenning and softenning caused by the dissolving of Fe and Cu respectively have been discussed based on the structure feature of NSSS and estimation of the strength of grain boundary and crystal components of NSSS.