Uncovering the mechanism of dislocation interaction with nanoscale (<4 nm) interphase precipitates in microalloyed ferritic steels

• Main Authors: Elena Pereloma, David Cortie, Navjeet Singh, Gilberto Casillas, Frank Niessen
• Format: Article
• Language: English
• Published: Taylor & Francis Group 2020-09-01
• Series: Materials Research Letters
• Subjects: interphase precipitation; precipitation strengthening; high resolution stem; dft modelling
• Online Access: http://dx.doi.org/10.1080/21663831.2020.1764121
• ISSN: 2166-3831

Nanoscale interphase precipitation in microalloyed ferritic steels provides a remarkable (200–400 MPa) strengthening increment, however its origin is unclear. Scanning transmission electron microscopy revealed step formation at the matrix/precipitate interface after both macroscopic uniaxial tension and nanopillar compression testing. Supported by Density Functional Theory modelling, dislocation shearing of nano-sized (<4 nm) VC precipitates was identified as a strengthening mechanism. The findings suggest the operation of an unusual {001}<110> slip–system in the VC nanoparticles.