Microstructure and properties of the Nd2Fe14Bp/Al–Co composites fabricated via microwave sintering

Abstract

This study aimed to fabricate a new type of aluminum matrix composite exhibiting high strength, good magnetic property, and toughness to solve the issues on current magnetic materials, such as brittleness and high density. In this paper, the Nd2Fe14Bp/Al–Co composites with different cobalt (Co) contents (wt.%) are fabricated via microwave sintering. The effects of the Co content on the composite microstructures and properties are studied. The results indicate that at a 580 °C sintering temperature, 30 min sintering time, and 30 °C/min heating rate, with an increase in the Co content (0 → 1%→2.5%→5%→7.5%→10%), the compactness initially increases and then decreases and reaches the maximum of 94.5% for the 5%Co sample together with a smaller grain size. The composites mainly consist of Nd2Fe14B with various sizes, Co particles, and the Nd2(Fe,Co)14B phase. The interfacial deformation resistance of the 5%Co sample tested via nanoindention is 22.8% higher than that of the Co-free sample, which can facilitate in the interfacial strengthening. The microhardness, yield strength, and tensile strength of the 5%Co samples are 107.4 HV, 210.84 MPa, and 139.8 MPa, respectively. The remanence Br, coercive force Hcj, and maximum magnetic energy product (BH)max of the 5%Co sample are 0.37 T, 0.65 T, and 45.12 kJ/m3, respectively, which are 48.6%, 29.2%, and 63.9% higher than those of the Co-free sample. The significant increase in the magnetic properties is mainly attributed to the interactive coupling between the Co particle soft magnetic phase and Nd2Fe14B hard magnetic phase.