Precipitation of Epsilon Copper in Ferrite Antibacterial Stainless Steel

The precipitation of epsilon copper at 1023 K ageing in ferrite antibacterial stainless steel was investigated by a combination of electron microscopy and micro-Vickers hardness measurement. The results show that epsilon copper precipitation occurs within 90 s. Complex rnultilayer structure confirmed as twins and stacking faults on {111}ε-Cu planes was observed in the precipitates. The precipitates grow by the lengthwise enlargement of a set of parallel layers, having 111]ε-Cu and 112]ε-Cu preferred growth orientations. The volume fraction of precipitates f formed within 120 min can be predicted by a modified Avrami equation (In 1/1-f= kt b).Simultaneously, substituent atom clusters with a size of 5-10 nm was found to occur in the solution and cause matrix strain. The precipitate morphology and distribution on the surface of ferrite antibacterial stainlesss teel are associated with surface crystallographic orientation of the matrix. The precipitates are predominantly located within the ferrite grains of <110> orientation. The precipitates located on {111}α-Fe surface planes have sphere or ellipse shape.