Microstructure and Mechanical Properties of Nanostructured Aluminum Consolidated by SPS

Abstract

Nanostructured aluminum powders were obtained by means of planetary ball milling with methanol as the Process Control Agent (PCA). The behavior, during milling, was considered measuring the microhardness and grain size at different milling times. Bulk near-full density samples were sintered using the Spark Plasma Sintering technology with different schedules: temperature of 500°C and 550°C, pressure of 30 MPa and 60 MPa and different modes of applying the pressure were changed in order to understand the behavior during sintering. The samples sintered at 500°C showed a density of about 2.4-2.61 g/cm3 while for that sintered at 550°C it was 2.65-2.67 g/cm3 depending on the applied pressure. All the samples retained their nanostructure with an increase of the grain size from about 46 up to 70-90 nm. Using X-ray diffraction and metallography the formation of Al4C3 carbides was detected for samples sintered at highest temperatures.

Safe radioisotope thermoelectric generators and heat sources for space applications

“…Given that polonium has a vaporisation temperature that is lower than the predicted SPS sintering temperature of Tungsten ($1500°C), production of a consolidated polonium-tungsten matrix may be challenging. Alternatively a polonium-aluminium substitute matrix could be produced since aluminium has been consolidated using an SPS furnace at around 500-550°C by Zadra et al [44] given that this is less than the vaporisation temperature of polonium. Such a consolidation would depend upon the existing GPHS module internal aeroshell to ensure safe re-entry of the cermet into the atmosphere but is likely to be able to maintain capture of the polonium loading.…”

Effects of annealing and extrusion on the microstructure and tensile properties of ultrafine-grained Al fabricated by spark plasma sintering

“…Bulk NC/UFG Al samples have been fabricated by SPS of NC Al powders produced by high-energy mechanical milling (HEMM) [4][5][6][7][8]. It was found that the grain growth was severely inhibited during SPS with the minimum grain size being down to 90 nm and its relative density being close to 100% [5]. Such NC/UFG Al samples can sustain strong grain boundary strengthening according to the Hall-Petch relationship [4].…”

Microstructure and Tensile Properties of Nanostructured and Ultrafine Grained FeMoB Alloys Produced by Spark Plasma Sintering of Mechanically Alloyed Powders

“…Powder consolidation was done by SPS, since this requires lower temperatures and much shorter times than conventional hot pressing techniques ( Ref 15,16). These characteristics make SPS particularly suitable to the processing of nanostructured powders ( Ref 3,7,8,[17][18][19][20][21].…”