Effect of cold-work on the Hall-Petch breakdown in copper based micro-components

Ehsan Ghassemali, Ming-Jen Tan, Chua Beng Wah, S.C.V. Lim, Anders E.W. Jarfors

Research output: Contribution to journalArticleResearchpeer-review

20 Citations (Scopus)


Effects of substructural dimensions on the mechanical properties of micro-pins produced by an open-die micro-extrusion/forging process were studied. Micro-pins of diameter 0.3 mm were manufactured from copper strips, having different initial grain sizes. Micro-compression tests on the micro-pins revealed no significant size effect, even if the number of grains over the diameter of the micro-pins falls below its critical value. However, relaxation of the as-formed substructure using recovery annealing led to a surprising drop in the flow stress of the micro-pins. This was explained and attributed to the number of subgrains over the diameter of the micro-pins, showing the important role of subgrains rather than grains in determining the mechanical properties.
Original languageEnglish
Pages (from-to)124 - 135
Number of pages12
JournalMechanics of Materials
Issue numberPart A
Publication statusPublished - 2015

Cite this