Prediction of grain structure evolution during rapid solidification of high energy density beam induced re-melting

Research output: Contribution to journalArticle

Authors

Colleges, School and Institutes

External organisations

  • University of Manchester

Abstract

Grain boundary migration in the presence of concentrated sources of heat is a complex process that has a considerable impact on resultant material properties. A phase eld model is presented incorporating thermal gradient and curvature driving force terms to predict how a poly-crystalline network evolves due to the application of such heat sources, as grain boundaries migrate due to local boundary curvature and time varying thermal gradients. Various thermal scenarios are investigated, in both two and three dimensions. These scenarios include both partial and full penetration laser induced melting, the application of a linearly varying time-independent thermal eld, and successive melting events where regions experience multiple melting and solidication cycles. Comparisons are made between the microstructures predicted by the proposed phase eld method, during the various thermal scenarios, that agree with commonly observed phenomena. Particularly interesting is the ability to explain the dier-ences in grain morphology between the full penetration and partial penetration welds using the phase eld model and associated driving force magnitudes between the two scenarios. The model predicts the restoration of grain boundary networks in regions experiencing multiple melting events, and explains the differences in grain morphology due to the local curvature and thermal gradient effects.

Details

Original languageEnglish
Pages (from-to)200-210
Number of pages11
JournalMaterials and Design
Volume147
Early online date15 Mar 2018
Publication statusPublished - 5 Jun 2018

Keywords

  • phase field , thermal field , re-melting , thermal gradient , grain boundary migration