Computational and experimental investigation of the strain rate sensitivity of small punch testing of the high-entropy alloy CoCrFeMnNi

DOI: 10.1016/j.jallcom.2022.168219

Authors: S. González (Northumbria University) , A. K. Sfikas (Northumbria University) , S. Kamnis (Castolin Eutectic-Monitor Coatings Ltd) , S. E. John (Swansea University) , Z. W. Nye (Swansea University) , M. Spink (Diamond Light Source) , C. Allen (Diamond Light Source; University of Oxford) , R. Martínez-Sánchez (Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología) , S. W. Naung (Northumbria University) , M. Rahmati (Northumbria University) , T. Keil (Technical University of Darmstadt) , K. Durst (Technical University of Darmstadt) , R. J. Lancaster (Swansea Universit)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Alloys And Compounds , VOL 210

State: Published (Approved)
Published: November 2022
Diamond Proposal Number(s): 28409

Abstract: The suitability of determining the strain rate sensitivity (SRS) of the CoCrFeMnNi high-entropy alloy (HEA) by small punch (SP) testing has been assessed at displacement rates ranging from 0.2 to 2 mm∙min-1. The stress was found to increase as the displacement rate was raised from 0.2 to 2 mm∙min-1, whereas the plastic strain distributions were similar in all cases. However, for a higher displacement rate of 10 mm∙min-1, the sample was found to exhibit a drop in strength and ductility attributed to casting defects. The strain-rate sensitivity exponent (m) was found to be 0.1387 whilst the Finite Element Analysis (FEA) simulations predicted a slightly smaller value of 0.1313. This latter value is closer to m = 0.091 obtained from nanoindentation strain rate jump tests since the results are insensitive to the presence of small casting defects. The relationship between the experimental and the empirically derived predicted properties from the SP tests revealed a high level of agreement for maximum stress properties. The properties predicted at 2 mm∙min-1 (R2 = 0.96) offered a stronger fit than at 0.5 mm∙min-1 (R2 = 0.92).

Journal Keywords: High entropy alloy; Small punch testing; Finite element simulation

Diamond Keywords: Alloys

Subject Areas: Materials, Engineering

Diamond Offline Facilities: Electron Physical Sciences Imaging Centre (ePSIC)
Instruments: E01-JEM ARM 200CF

Added On: 30/11/2022 09:49

Documents:
1-s2.0-S0925838822046102-main.pdf

Discipline Tags:

Materials Engineering & Processes Materials Science Engineering & Technology Metallurgy

Technical Tags:

Microscopy Electron Microscopy (EM) Transmission Electron Microscopy (TEM)