Abstract
Gadolinia (Gd2O3) is potentially attractive as a dispersive phase for copper matrix composites due to its excellent thermodynamic stability. In this paper, a series of 1.5 vol% nano-Gd2O3/Cu composites were prepared via an internal oxidation method followed by powder metallurgy in the temperature range of 1123–1223 K with a holding time of 5–60 min. The effects of processing parameters on the microstructure and properties of the composites were analyzed. The results showed that the tensile strength and conductivity of the nano-Gd2O3/Cu composite have a strong link with the microporosity and grain size, while the microstructure of the composite was determined by the sintering temperature and holding time. The optimal sintering temperature and holding time for the composite were 1173 K and 30 min, respectively, under which a maximum ultimate tensile strength of 317 MPa was obtained, and the conductivity was 96.8% IACS. Transmission electron microscopy observations indicated that nano-Gd2O3 particles with a mean size of 76 nm formed a semi-coherent interface with the copper matrix. In the nano-Gd2O3/Cu composite, grain-boundary strengthening, Orowan strengthening, thermal mismatch strengthening, and load transfer strengthening mechanisms occurred simultaneously.
Highlights
Owing to its high electrical and thermal conductivities, good corrosion resistance, and ease of fabrication [1,2,3,4], copper and its alloys are widely used in electrical equipment such as wiring and motors, and it has uses in construction for plumbing, industrial machinery, and the divertor components for a fusion reactor
The sintering temperature should be slightly lower than the melting point of the basic elements of the composite [25], so temperatures ranging from 1123 to 1223 K were chosen for making the nano-Gd2O3/Cu composite, and the holding time was set to 5–60 min
The process parameter optimization was evaluated by measuring the tensile strength and conductivity of the nano-Gd2O3/Cu composite made with different sintering temperatures and holding times in the sintering process
Summary
Owing to its high electrical and thermal conductivities, good corrosion resistance, and ease of fabrication [1,2,3,4], copper and its alloys are widely used in electrical equipment such as wiring and motors, and it has uses in construction for plumbing, industrial machinery (such as heat exchangers), and the divertor components for a fusion reactor. The weak mechanical properties and poor wear resistance of pure copper limit its service life [5,6,7,8]. Cu-1.5 wt.% Al2O3 composites were synthesized by mechanical alloying and hot extrusion, which showed a maximum compressive strength of 525 MPa [9]. The composite had a weak interface between the Al2O3 particle and the Cu matrix due to their poor surface wettability. To improve their interfacial bonding, Cu-Cr-Al2O3 composites were fabricated by mechanical milling and vacuum hot pressing [10]. The electrical conductivity of the Cu-Cr-Al2O3 composites was only about 60% IACS
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