title: Avalanches in compressed Ti-Ni shape-memory porous alloys: An acoustic emission study.
abstract: Mechanical avalanches during compression of martensitic porous Ti-Ni have been characterized by high-frequency acoustic emission (AE). Two sequences of AE signals were found in the same sample. The first sequence is mainly generated by detwinning at the early stages of compression while fracture dominates the later stages. Fracture also determines the catastrophic failure (big crash). For high-porosity samples, the AE energies of both sequences display power-law distributions with exponents ɛ≃2 (twinning) and 1.7 (fracture). The two power laws confirm that twinning and fracture both lead to avalanche criticality during compression. As twinning precedes fracture, the observation of twinning allows us to predict incipient fracture of the porous shape memory material as an early warning sign (i.e., in bone implants) before the fracture collapse actually happens.
authors.affiliation: Departament d'Estructura i Constituents de la Matèria, Facultat de Física, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona, Catalonia, Spain.|Centro de Investigación en Materiales Avanzados. S.C. Miguel de Cervantes 120, Complejo Industrial Chihuahua. 31109 Chihuahua, Mexico.
authors.forename: Daniel
authors.initials: D
authors.lastname: Soto-Parra
authors.affiliation: Department of Metallic Materials Science & Engineering, School of Materials Science & Engineering, South China University of Technology, Wushan 510640, Guangzhou, People's Republic of China.
authors.forename: Xiaoxin
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Metallic Materials Science & Engineering, School of Materials Science & Engineering, South China University of Technology, Wushan 510640, Guangzhou, People's Republic of China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Cao
authors.affiliation: Departament d'Estructura i Constituents de la Matèria, Facultat de Física, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona, Catalonia, Spain.
authors.forename: Eduard
authors.initials: E
authors.lastname: Vives
authors.affiliation: Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, United Kingdom.
authors.forename: Ekhard K H
authors.initials: EK
authors.lastname: Salje
authors.affiliation: Departament d'Estructura i Constituents de la Matèria, Facultat de Física, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona, Catalonia, Spain.
authors.forename: Antoni
authors.initials: A
authors.lastname: Planes