Densification Behavior and Microstructural Development of Nano-Agglomerate Powder during Sintering

Abstract

Densification behavior of nano-agglomerate powder during pressureless sintering of Fe-Ni nanopowder was investigated in terms of diffusion kinetics and microstructural development. To understand the role of agglomerate boundary for sintering process, densification kinetics of Fe-Ni nano-agglomerate powder with different agglomerate size was investigated. It was found that activation energy for densification process was lower in the small-sized agglomerate powder. The increase in the volume fraction of inter-agglomerate boundary acting as high diffusion path might be responsible for the enhanced diffusion process.

Consolidation of Hierarchy-Structured Nanopowder Agglomerates and Its Application to Net-Shaping Nanopowder Materials

“…In order to examine the role of agglomerate boundary of hierarchical structured nanopowder in sintering kinetics, densification kinetics for Fe–8 wt % Ni nanopowder agglomerate compacts with different agglomerate size of 5 and 500 μm was investigated in terms of the activation energy for densification process [24]. The parameters required to calculate activation energy on the basis of Equation (1) were obtained from the result of densification process during heat-up sintering at various heating rates: $\ln false(\frac{\varphi }{T^2}false)=\ln false(\frac{CR}{Y^{n}Q}false)-\frac{Q}{RT}$ where ϕ is the ratio of the heating rate, T is temperature, R is gas constant, Y is the identical value of shrinkage and Q is activation energy for densification [24].…”

“…Apparent activation energy for densification process for Fe–8 wt % Ni nanopowder agglomerates during sintering at intermediate temperatures [24]. …”