Critical microstructures and defects in heterostructured materials and their effects on mechanical properties. (1st May 2020)

• Record Type: Journal Article
• Authors: Liu, Yanfang; Cao, Yang; Mao, Qingzhong; Zhou, Hao; Zhao, Yonghao; Jiang, Wei; Liu, Ying; Wang, Jing Tao; You, Zesheng; Zhu, Yuntian
• Is Part Of: Acta materialia. Volume 189(2020)
• Page Start: 129
• Page End: 144
• Publication Date: 2020-05-01
• Subjects: Heterostructure -- Hetero-deformation induced (HDI) hardening -- Back-stress -- Shear band -- Slip band; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2020.03.001
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: Systematic study was conducted on the microstructures and mechanical properties of nickel samples with two distinct types of heterostructures. The first is featured with coarse-grained lamellae embedded in a matrix consisting of a very high density of dislocation structures. The second is featured with coarse-grained zones embedded in the ultrafine-grained matrix. The second type of heterostructures exhibits better strength and ductility, although it has a smaller average grain size than the first type. The zone boundaries in the second type of heterostructures are less prone to cracking than those in the first type. Intersecting micro-shear-bands formed net-like patterns in the second type of heterostructures during tensile deformation. This is the first ever observation of structural micro-shear-bands in a heterostructured material. It supports the claim that heterostructure promotes the formation of dispersive shear bands. In contrast, a macroscopic shear band formed and caused early failure of the sample with the first type of heterostructures. Our results indicate that well-developed ultrafine/nano grained matrix in heterostructured materials are necessary for preventing crack formation and shear band localization. This should be considered as a key factor for optimizing the mechanical properties of heterostructured materials. Graphical abstract: Image, graphical abstract