Effects of single/double stage cold rolling and aging treatment on the α-Fe phase, microstructure, and properties of Cu–12Fe-0.42Si-0.008B alloy

Abstract

Cu–12Fe-0.42Si-0.008B alloy was formed by twin-roll strip casting. Studied the strengthening mechanism after adding Si and B elements and the effect of single/double stage cold rolling aging on its microstructure and properties. The solidification structure of the two alloys was dominated by equiaxed grains, with a “sandwich” structure formed by the Cu and the central Fe-rich phases. The tensile strength of the alloy increases with the increase of aging time. The maximum strength at 16 h of two-stage cold rolling and aging (450 °C) is 682.2 MPa, 52% higher than that of the Cu–12Fe alloy, and the saturation magnetic field strength increased by 29.4 %. This is attributed to the addition of Si and B elements to increase the number of primary iron-rich phases in the alloy and promote the precipitation of nano-α-Fe phase during aging. The finer nano-Fe-rich phase particles are generated with a coherent relationship between the precipitated Fe phase and the Cu bas, that is (1-1-1)Cu//(10-1)Fe. The strength of the alloy after two-stage cold rolling aging is always better than that of single-stage cold rolling. This is because the two-stage cold rolling treatment reduces the content of fibrous α - Fe phase in the alloy and increases the nanoscale spherical α-Fe phase. Confirming that the spherical α-Fe phase has a better strengthening effect. The relative conductivity of alloy increases with the increased aging time, with the highest relative conductivity of 53.9% IACS and 54.9% IACS obtained after 16 h of two-stage cold rolling aging.

Keywords

• Cu-12Fe-0.42Si-0.008B alloy
• Twin-roll strip casting
• Microstructure
• Mechanical properties
• Aging heat treatment
• Electrical conductivity