Abstract
Due to its outstanding ductility over a large temperature range, equiatomic HfNbTaTiZr is well-suited for investigating the influence of temperature and plastic strain on deformation mechanisms in concentrated, body centered cubic solid solutions. For this purpose, compression tests in a temperature range from 77 up to 1073 K were performed and terminated at varying plastic strains for comparison of plastic deformation behavior. The microstructure and chemical homogeneity of a homogenized HfNbTaTiZr ingot were evaluated on different length scales. The compression tests reveal that test temperature significantly influences yield strength as well as work hardening behavior. Electron backscatter diffraction aids in shedding light on the acting deformation mechanisms at various temperatures and strains. It is revealed that kink band formation contributes to plastic deformation only in a certain temperature range. Additionally, the kink band misorientation angle distribution significantly differs at varying plastic strains.
Highlights
Metals and alloys usually deform plastically by dislocation slip or by deformation twinning if diffusion-based processes are excluded.In body centered cubic metals and alloys, pencil glide occurs in {011}, {132} and{121} 21 h111i slip systems, whereas twinning is found in a {112} 16 h111i-type system [1,2].localized deformation mechanisms can be active in metals and alloys, such as the formation of kink bands
The chemical homogeneity of homogenized HfNbTaTiZr was evaluated by X-ray diffraction (XRD), electron channeling contrast imaging (ECC) imaging, EDX mapping, and atom probe tomography (APT) on different length scales
In equiatomic HfNbTaTiZr, kink band formation as a localized deformation mechkink bands could already be observed at low plastic strains of 1.9%
Summary
Localized deformation mechanisms can be active in metals and alloys, such as the formation of kink bands. Kink band formation was firstly described by Orowan [3] as a mechanism that can be neither assigned to uniform dislocation slip nor to deformation twinning. Kink bands form by highly localized dislocation-mediated rotation of one crystal/crystallite segment by a certain misorientation angle with respect to the non-kinked segment. The misorientation angle of the kinked region does not necessarily possess an obvious crystallographic relationship to the undeformed crystal [3]. This property unambiguously distinguishes kink bands from deformation twins [3]. For bcc metals and alloys with h111i slip directions and potential {011},
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