Nanostructured Cu-based alloys by Spark Plasma Sintering of Mechanically alloyed powders: Structure and CharacterizationThursday (29.09.2016) 11:45 - 12:00 Part of:
Metals and their alloys with a grain size on a nano and submicron scale are of special interest because of their exceptional mechanical and physical properties. Nanostructured metal-matrix Cu-based composites such as Cu–Cr, Cu–W, Cu–Mo (also called pseudo-alloys) are of current interest due to unique combination of their mechanical, electrical, and thermo-physical properties [1–3]. The combination of refractory metals such as Cr, Mo, W with a low-melting metal (e.g. Cu) affords tailoring composite materials for a wide variety of applications, including heat-sink elements in microelectronic devices, contacts in high-voltage circuit breakers, nozzles for rocket engines. Analysis of the available literature shows that, for electrotechnical applications nanostructured pseudo-alloys are advantageous over conventional micro-sized composites [4,5]. The production of high-quality Cu-based pseudo-alloys require that starting components be uniform and intermixed on a submicron or nano level. A drawback of such composites is low mutual solubility, high difference between their melting points and densities, and high wetting angle .
In present study, a technological approach based on optimal combination of high-energy ball milling (HEBM) and spark plasma sintering (SPS) was used as an effective tool for fabrication of Cu–Cr, Cu–W, and Cu–Mo nanostructured dense materials.
A set of nanocomposite Cu–Cr, Cu–Mo, Cu-W powders were prepared by high-energy ball milling for up to 60 min and then consolidated by short-term SPS (10 min) at 700–950ºC under pressure (50 MPa) to obtain almost pore-free pseudo-alloys.
Microstructure, crystal structure, and local atomic structure were characterized by XRD, high-resolution SEM, and high-resolution TEM.
Thus prepared nanocomposites showed a Vickers microhardness and an electrical resistivity of up to 5.3GPa and 6–9.6 μΩ cm for Cu–Cr; up to 3.8 GPa and 6.1–6.2 μΩ cm for Cu–Mo; which makes them promising candidates for application as electric contact materials.
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