The ductile-brittle transition for nominally pure polycrystalline nickel

S. Mahalingam*, P. E. J. Flewitt, J. F. Knott

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

21 Citations (Scopus)

Abstract

A ductile to brittle transition has been observed for a nominally high purity polycrystalline nickel of similar to 200 mu m grain size, containing 50 ppm sulphur. The nickel specimens were subjected to heat treatment at 1017 degrees C for 0.5 h and were then either furnace cooled or water quenched. Small notched bend geometry specimens were tested over the temperature range of -196 degrees C to 200 degrees C at a fixed strain rate. Both the work to initiate fracture and the proportion of intergranular fracture were determined. The elemental concentration of sulphur at the grain boundaries has been measured using scanning Auger spectroscopy and STEM-EDX microanalysis. These compositions are compared with predictions from a non-equilibrium segregation model. The segregation of sulphur to the grain boundaries has a strong effect in promoting brittle intergranular fracture and this is attributed to the change in cohesive strength of the grain boundaries as a result of the segregation. (c) 2012 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)342-350
Number of pages9
JournalMaterials Science and Engineering: A
Volume564
DOIs
Publication statusPublished - 1 Mar 2013

Keywords

  • Polycrystalline nickel
  • Small scale bend specimen
  • Sulphur
  • Non-equilibrium segregation
  • Ductile-brittle transition temperature
  • AUGER-ELECTRON SPECTROSCOPY
  • GRAIN-BOUNDARY SEGREGATION
  • INTERGRANULAR FRACTURE
  • TEMPER EMBRITTLEMENT
  • SULFUR SYSTEM
  • ALLOYS
  • STEELS
  • INTERFACES

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