Crystalline-amorphous-crystalline two-step phase transformation and the resulting supra-nano structure in a metastable iron-based alloy

Xu Wang, Yingqian Fu, Yidong Wu, Jianbiao Wang, Jitang Fan, Fei Zhang, Haihui Ruan, Yuan Wu

Research output: Journal article publicationJournal articleAcademic researchpeer-review


In this work, we report a crystalline-amorphous-crystalline (CAC) two-step solid-state phase transformation (SSPT) in a 15Cr-2Ni iron-based alloy that results in nanostructures. Microstructurally, the CAC process leads to a localized supra-nano structure having almost equal content of an amorphous matrix and nanocrystalline inclusions less than 6 nm. Dynamically, it is manifested as a glass-transition-like variation of Young's modulus with a sharp surge in internal friction. Through in situ heating and Neutron Scattering experiments, a reduction in the intensities of the austenite diffraction peaks is observed, which is not associated with any intensity increase in other peaks, suggesting the collapse of austenite lattice during heating. The CAC two-step SSPT occurs at temperatures far below the melting point, and the introduction of the dislocations is the indispensable condition giving rise to such a transition. Based on experimental results, we suggest the physical picture of CAC two-step SSPT and a phenomenological model to describe it. Through the analysis, we argue that the CAC two-step SSPT provides a new route to fabricate nanostructured alloys.

Original languageEnglish
Article number119690
JournalActa Materialia
Publication statusPublished - 1 Mar 2024


  • Kinetic analysis
  • Neutron diffraction
  • Order-disorder phenomena
  • Solid state phase transformation
  • Supra-nano ultrastructure

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys


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