Understanding plasticity in irradiated alloys through TEM in situ compression pillar tests. Issue 8 (28th April 2020)

• Record Type: Journal Article
• Authors: Qu, Haozheng J.; Yano, Kayla H.; Patki, Priyam V.; Swenson, Matthew J.; Wharry, Janelle P.
• Is Part Of: Journal of materials research. Volume 35:Issue 8(2020)
• Page Start: 1037
• Page End: 1050
• Publication Date: 2020-04-28
• Subjects: radiation effects, -- transmission electron microscopy, -- stress/strain relationship; Materials -- Research -- Periodicals; 620.1105
• DOI: 10.1557/jmr.2019.295
• Languages: English
• ISSNs: 0884-2914

Abstract

Abstract: Abstract : Depth-sensing transmission electron microscopic (TEM) in situ mechanical testing has become widely utilized for understanding deformation in irradiated materials. Until now, compression pillars have primarily been used to study the elastic properties and yield of irradiated materials. In this study, we utilize TEM in situ compression pillars to investigate plastic deformation in two ion-irradiated alloys: Fe–9% Cr oxide dispersion strengthened (ODS) alloy and nanocrystalline Cu–24% Ta. We develop an algorithm to automate the extraction of instantaneous pillar dimensions from TEM videos, which we use to calculate true stress–strain curves and strain hardening exponents. True stress–strain curves reveal intermitted plastic flow in all specimen conditions. In the Fe–9% Cr ODS, intermitted plastic flow is linked to strain bursts observed in TEM videos. Low strain hardening or strain softening is observed in all specimen conditions. TEM videos link the strain softening in irradiated Fe–9% Cr ODS to dislocation cross-slip, and in Cu–24% Ta to grain boundary sliding.