Imperial College London
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ProfessorPeterLee

Faculty of Engineering, Department of Materials

Visiting Professor
 
 
 
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Contact

 

+44 (0)20 7594 6801p.d.lee

 
 
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Location

 

102Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Prasad:2020:10.1016/j.actamat.2020.05.012,
author = {Prasad, A and Yuan, L and Lee, P and Patel, M and Qiu, D and Easton, M and StJohn, D},
doi = {10.1016/j.actamat.2020.05.012},
journal = {Acta Materialia},
pages = {392--403},
title = {Towards understanding grain nucleation under Additive Manufacturing solidification conditions},
url = {http://dx.doi.org/10.1016/j.actamat.2020.05.012},
volume = {195},
year = {2020}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - This paper provides insights into the effect of high thermal gradients and cooling rates on equiaxed grain nucleation and growth in conditions similar to those experienced during Additive Manufacturing (AM) processes. Bridgman type solidification is numerically simulated with columnar grains growing at a fixed pull rate under a user-imposed thermal gradient. Controlled inoculants of known nucleation undercooling were placed ahead of the growing columnar grains to allow quantitative analysis of nucleation events. At low thermal gradient and cooling rate only the inoculants with low nucleation undercooling were activated due to low melt undercooling driven by constitutional supercooling (CS). As the cooling rate is increased, for a given thermal gradient, a larger number of inoculants with higher nucleation undercoolings were activated. At higher cooling rates, thermal undercooling was generated by a lag in the growth rate of the solid-liquid (S–L) interface compared to the theoretical pull rate. Thus, thermal undercooling becomes dominant leading to the facilitation of nucleation on less potent substrates requiring higher undercooling. The results show a transition from solute-driven undercooling to cooling rate driven thermal undercooling which contributes to the undercooling that activates the nucleation events. Invoking the Interdependence model, it is also shown that the high cooling rate induced thermal undercooling reduces the size of the nucleation free zone substantially.
AU  - Prasad,A
AU  - Yuan,L
AU  - Lee,P
AU  - Patel,M
AU  - Qiu,D
AU  - Easton,M
AU  - StJohn,D
DO  - 10.1016/j.actamat.2020.05.012
EP  - 403
PY  - 2020///
SN  - 1359-6454
SP  - 392
TI  - Towards understanding grain nucleation under Additive Manufacturing solidification conditions
T2  - Acta Materialia
UR  - http://dx.doi.org/10.1016/j.actamat.2020.05.012
UR  - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000552116400036&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR  - https://www.sciencedirect.com/science/article/pii/S1359645420303517?via%3Dihub
UR  - http://hdl.handle.net/10044/1/84735
VL  - 195
ER  -
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