Mechanism of FIB-Induced Phase Transformation in Austenitic Steel

Joseph R. Michael, Lucille A. Giannuzzi, M. Grace Burke, Xiang Li Zhong

Research output: Contribution to journalArticlepeer-review


The transformation of unstable austenite to ferrite or α′ martensite as a result of exposure to Xe+ or Ga+ ions at room temperature was studied in a 304 stainless steel casting alloy. Controlled Xe+ and Ga+ ion beam exposures of the 304 were carried out at a variety of beam/sample geometries. It was found that both Ga+ and Xe+ ion irradiation resulted in the transformation of the austenite to either ferrite or α′ martensite. In this paper, we will refer to the transformation product as a BCC phase. The crystallographic orientation of the transformed area was controlled by the orientation of the austenite grain and was consistent with either the Nishiyama-Wasserman or the Kurdjumov-Sachs orientation relationships. On the basis of the Xe+ and Ga+ ion beam exposures, the transformation is not controlled by the chemical stabilization of the BCC phase by the ion species, but is a result of the disorder caused by the ion-induced recoil motion and subsequent return of the disordered region to a more energetically favorable phase.

Original languageEnglish
Pages (from-to)70-82
Number of pages13
JournalMicroscopy and Microanalysis
Issue number1
Publication statusPublished - 23 Feb 2022


  • austenite
  • FIB
  • gallium
  • phase transformation
  • xenon


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