TY - JOUR
T1 - Effect of microgravity on grain coarsening during liquid phase sintering in the Fe-Cu system
AU - Naser, J.
AU - Smith, J. E.
AU - Kuruvilla, A. K.
N1 - Funding Information:
This work was supported by NASA under grant NAGW-812 to the Consortium for Materials Development in Space at The University of Alabama in Huntsville. Engineering support was also provided by Wyle Laboratories and Teledyne Advanced Materials. The assistance provided by C. K. L. Davies, P. Nash and R. N. Stevens with the LSEM model is gratefully acknowledged. Numerous individuals from both academia and corporate industrial partners lent their knowledge, cooperation and support throughout this project.
PY - 1998
Y1 - 1998
N2 - Samples within the Fe-Cu system with three different volume fractions of solid (50, 60 and 70 vol % Fe) and four different sintering times (2.5, 5, 17 and 66 min) were liquid phase sintered (LPS) in microgravity. Particle coarsening during LPS is generally known to increase with increasing volume fraction of solid. Contrary to expectations, there was an enhancement in particle coarsening with a decrease in the volume fraction of solid. The agglomerated microstructures observed in these samples (especially those with a lower volume fraction of solid) also exhibited a higher grain growth constant consistent with their higher 3D coordination number. The relevant analysis discussed in this paper strongly suggests that agglomeration is promoted by Brownian motion that dominates any density-driven force in the absence of gravity. The observed particle growth characteristics were in excellent agreement with the Lifshitz-Slyozov encounter modified theory, which incorporates the effect of higher solid volume fraction and particle coalescence into the LSW theory. The particle distributions appear to remain unchanged with processing time beyond 2.5 min, suggesting thereby, that agglomeration promotes an equilibrium particle configuration early on in the process and enables scaled grain growth with time.
AB - Samples within the Fe-Cu system with three different volume fractions of solid (50, 60 and 70 vol % Fe) and four different sintering times (2.5, 5, 17 and 66 min) were liquid phase sintered (LPS) in microgravity. Particle coarsening during LPS is generally known to increase with increasing volume fraction of solid. Contrary to expectations, there was an enhancement in particle coarsening with a decrease in the volume fraction of solid. The agglomerated microstructures observed in these samples (especially those with a lower volume fraction of solid) also exhibited a higher grain growth constant consistent with their higher 3D coordination number. The relevant analysis discussed in this paper strongly suggests that agglomeration is promoted by Brownian motion that dominates any density-driven force in the absence of gravity. The observed particle growth characteristics were in excellent agreement with the Lifshitz-Slyozov encounter modified theory, which incorporates the effect of higher solid volume fraction and particle coalescence into the LSW theory. The particle distributions appear to remain unchanged with processing time beyond 2.5 min, suggesting thereby, that agglomeration promotes an equilibrium particle configuration early on in the process and enables scaled grain growth with time.
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U2 - 10.1023/A:1004403912910
DO - 10.1023/A:1004403912910
M3 - Article
AN - SCOPUS:0032281797
SN - 0022-2461
VL - 33
SP - 5573
EP - 5580
JO - Journal of Materials Science
JF - Journal of Materials Science
IS - 23
ER -