Densification behavior of mechanically milled Cu–8at% Cr alloy and its mechanical and electrical properties

Abstract

Synthesis and consolidation behavior of Cu-8 at% Cr alloy powders made by mechanical alloying with elemental Cu and Cr powders, and subsequently, compressive and electrical properties of the consolidated alloys were studied. Solid solubility of Cr in Cu during milling, and subsequent phase transformations during sintering and heat treatment of sintered components were analyzed using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The milled powders were compacted applying three different pressures (200 MPa, 400 MPa and 600 MPa) and sintered in H 2 atmosphere at 900 1C for 30 min and at 1000 1C for 1 h and 2 h. The maximum densification (92.8%) was achieved for the sample compacted at 600 MPa and sintered for 1000 1C for 2 h. Hardness and densification behavior further increased for the compacts sintered at 900 1C for 30 min after rolling and annealing process. TEM investigation of the sintered compacts revealed the bimodal distribution of Cu grains with nano-sized Cr and Cr 2 O 3 precipitation along the grain boundary as well as in grain interior. Pinning of grain boundaries by the precipitates stabilized the fine grain structure in bimodal distribution.

Effect of Nanopowder Addition on the Sintering of Water-Atomized Iron Powder

“…To understand the impact of nanopowder addition on the density, the densification parameter was used. [12] An increase in the parameter value was observed, which means that the extent of densification increased with increasing nanopowder content. From a value of 0.14 for the compact with 5 wt pct nanopowder, it increased to approximately 0.45 for the compact with 20 wt pct nanopowder.…”

“…The densification parameter was used to evaluate the ability of the compact to densify during sintering. This parameter was calculated using the following formula [12] :…”

The formation kinetics of Cr2O3dispersed Cu synthesized by Cryo-milling

“…The similar observation can be found in other reports where the high coarsening behavior of Cr 2 O 3 dispersoids ended up with the globular dispersoids of even 2-5 µm in size after internal oxidation processing at 1176-1325 K. As a consequence, the low Vickers hardness number from 90-140 (Hv) depending on the percent of Cr oxide was observed. The other results likewise reveal that the Cr 2 O 3 does not lead to the effective strengthening effect for its coarsening nature after hot consolidation [4,5,15]. It is noticeable here that the Al 2 O 3 dispersoids remains small, even after recrystallization of the matrix takes place [6,7,9,17].…”

The Influence of Induction Sintering on Microstructure and Deformation Behavior of Ti-5Al-5Mo-5V-3Cr Alloy

“…where q s is the density of the compact after sintering, q g is the density of the compact after the cold compacting process, and q t is the theoretical density of the solid material. [28] Similarly to the relative density values, the densification parameter increases with increasing sintering temperature up to 1250°C, and it is about 0.07 higher compared to that obtained by the sintering at 1000°C (0.24 and 0.17, respectively).…”