Grain size dependence of fracture toughness and crack-growth resistance of superelastic NiTi. (1st March 2016)

• Record Type: Journal Article
• Authors: Ahadi, Aslan; Sun, Qingping
• Is Part Of: Scripta materialia. Volume 113(2016)
• Page Start: 171
• Page End: 175
• Publication Date: 2016-03-01
• Subjects: Shape memory alloys -- Martensitic phase transformation -- Microstructure -- Toughness -- Intrinsic and extrinsic toughening mechanisms; Materials -- Periodicals; Metallurgy -- Periodicals; Metalen; Legeringen; Materiaalkunde; Metals, metalworking and machinery industries; Metals; Electronic journals; 620.11
• DOI: 10.1016/j.scriptamat.2015.10.036
• Languages: English
• ISSNs: 1359-6462

Abstract

Abstract: The grain size (GS) dependence of fracture toughness ( K IC ) and static crack-growth resistance ( K R ) of superelastic NiTi with average GS from 10 to 1500 nm are investigated. The measurements of strain and temperature fields at the crack-tip region are synchronized with the force–displacement curves under mode-I crack opening tests. It is found that with GS reduction down to nanoscale, the K IC and the size of crack-tip phase transformation zone monotonically decrease and the K R changes from a rising to a flat R-curve. The roles of intrinsic and extrinsic toughening mechanisms in the GS dependence of the fracture process are discussed. Graphical abstract: