Production of a nanostructured copper by Spark Plasma Sintering

The aim of the present PhD work is the study of the production of a nanostructured copper by Spark Plasma Sintering. The nanostructured powder was produced by cryomilling an atomized powder, using a ball-to-powder ratio of 30:1 for 8h; it has a mean grain size of 19±2 nm and shows quite a high thermal stability, as shown by a DSC investigation. The influence of temperature, particle size, pressure on the densification and sintering mechanisms as well as that of heating rate and holding time on the structural evolution has been investigated. Particle rearrangement, local deformation, bulk deformation and sintering are the SPS mechanisms occurring successively during the sintering process of the atomized copper. These mechanisms are enhanced by the peculiar heating mechanism in SPS, and the surface overheating above the melting temperature in the contact regions has been demonstrated. In the cryomilled powder, sintering occurs at much lower temperature than in the atomized powder, due to effect of the high density of structural defects on the mass transport phenomena responsible for neck growth. The increase in heating rate tends to promote a bimodal grain size distribution (both nanomentric and ultrafine grains) while an increase in holding time increases grain size slightly. A promising combination of strength and ductility was measured on tensile specimens produced under selected conditions, and a dimpled fracture morphology was observed.

Grantor dc:publisher

Università degli studi di Trento

Year dc:date

2013

Author dc:creator

• Diouf, Saliou

Contributors dc:contributor

• Molinari, Alberto

• Settore ING-IND/21 - Metallurgia

Statement dc:rights

• info:eu-repo/semantics/openAccess
• license:Tutti i diritti riservati (All rights reserved)

Language dc:language

eng

Identifier

http://dx.doi.org/10.15168/11572_368839
10.15168/11572_368839

OAI identifier oai:identifier

oai:iris.unitn.it:11572/368839