“…Furthermore, the point-to-point correspondence between stress (or strain) and apparent Young’s modulus because of the elastic softening phenomenon make the alloy available for applications requiring different material stiffness at certain stress (or strain) ranges. The ease of large-scale production of bulk single crystals with a controllable orientation by cyclic heat treatment and the low cost make the present alloy particularly advantageous for these applications 31 , 32 , 45 . Fig.…”
Section: Discussionmentioning
confidence: 99%
“…Then, the sheet specimens were sandwiched between Mo sheets and subjected to a cyclic heat treatment. In this manner, large <100> single crystal sheet specimens could be obtained 45 . Additionally, sheet specimens cut from the noncolumnar area of the ingots were subjected to cyclic heat treatment to obtain large single crystals with other orientations along the length direction.…”
Crystalline metals can have large theoretical elastic strain limits. However, a macroscopic block of conventional crystalline metals practically suffers a very limited elastic deformation of <0.5% with a linear stress–strain relationship obeying Hooke’s law. Here, we report on the experimental observation of a large tensile elastic deformation with an elastic strain of >4.3% in a Cu-based single crystalline alloy at its bulk scale at room temperature. The large macroscopic elastic strain that originates from the reversible lattice strain of a single phase is demonstrated by in situ microstructure and neutron diffraction observations. Furthermore, the elastic reversible deformation, which is nonhysteretic and quasilinear, is associated with a pronounced elastic softening phenomenon. The increase in the stress gives rise to a reduced Young’s modulus, unlike the traditional Hooke’s law behaviour. The experimental discovery of a non-Hookean large elastic deformation offers the potential for the development of bulk crystalline metals as high-performance mechanical springs or for new applications via “elastic strain engineering.”
“…Furthermore, the point-to-point correspondence between stress (or strain) and apparent Young’s modulus because of the elastic softening phenomenon make the alloy available for applications requiring different material stiffness at certain stress (or strain) ranges. The ease of large-scale production of bulk single crystals with a controllable orientation by cyclic heat treatment and the low cost make the present alloy particularly advantageous for these applications 31 , 32 , 45 . Fig.…”
Section: Discussionmentioning
confidence: 99%
“…Then, the sheet specimens were sandwiched between Mo sheets and subjected to a cyclic heat treatment. In this manner, large <100> single crystal sheet specimens could be obtained 45 . Additionally, sheet specimens cut from the noncolumnar area of the ingots were subjected to cyclic heat treatment to obtain large single crystals with other orientations along the length direction.…”
Crystalline metals can have large theoretical elastic strain limits. However, a macroscopic block of conventional crystalline metals practically suffers a very limited elastic deformation of <0.5% with a linear stress–strain relationship obeying Hooke’s law. Here, we report on the experimental observation of a large tensile elastic deformation with an elastic strain of >4.3% in a Cu-based single crystalline alloy at its bulk scale at room temperature. The large macroscopic elastic strain that originates from the reversible lattice strain of a single phase is demonstrated by in situ microstructure and neutron diffraction observations. Furthermore, the elastic reversible deformation, which is nonhysteretic and quasilinear, is associated with a pronounced elastic softening phenomenon. The increase in the stress gives rise to a reduced Young’s modulus, unlike the traditional Hooke’s law behaviour. The experimental discovery of a non-Hookean large elastic deformation offers the potential for the development of bulk crystalline metals as high-performance mechanical springs or for new applications via “elastic strain engineering.”
“…More recently, the Cu-Al-Mn SMA system, which was first reported in 1995 by Kainuma et al [9,94], has been receiving great attention in the literature. This is attributed to the recent development of metal alloy manufacturing processes that allow the production of these SMAs with adequate control of texture and grain size, enabling the achievement of superior superelastic properties than those of traditional Cu-Al-Ni and Cu-Al-Zn SMA systems [9,61,95]. Cu-Al-Mn SMA generally have an Al content of less than 18 at% and show excellent ductility and good shape memory effect mainly due to the low degree of ordering of their L2 1 parent phase [9,68,94].…”
Cu-based shape memory alloys belong to one important class of functional alloys, presenting shape memory effect and superelasticity due to their reversible martensitic transformation. Although they have been extensively studied since the middle of the last century, there are still many challenges to be solved. In the last decades, these alloys were extensively studied regarding new compositions, processing routes, phase transformation, mechanical and functional properties. Aspects of the thermoelastic phase transformation have been described using thermodynamic and thermo-mechanical studies, while the role of metallurgical features (such as grain size and morphology, ordering, precipitates and second phases) have been described mainly by phenomenological approach. In this sense this review discusses the advances in the general fundamentals of Cu-based shape memory alloys, the recent developments in processing routes, compositions, and applications in the last years.
Graphical abstract
“…(2) AGG may be driven by sub-grains boundary energy. Sub-grains are introduced by the phase transitions in iron-based and copper-based sheets during thermal cycling, and sub-grains boundary energy can drive grains to grow abnormally [13][14][15][16]. (3) AGG may be related to grain boundary energy and grain boundary mobility.…”
The abnormal grain growth behaviour and preferential orientation of AZ31 Mg alloy were systematically examined. Abnormal grain growth was observed after annealing at 500°C for 9 h, and the grain growth rate was 1.3 mm h−1. Due to the abnormal grain growth, the activation energy of grain growth was reduced from 172 to 104 KJ mol−1. The abnormal grains with <11 [Formula: see text] 0> orientation grew preferentially, which resulted in the increase of the <11 [Formula: see text] 0> type texture intensity and the decrease of the <0001>. The energy difference of the misorientation is the main driving force for the formation of abnormal grains with <11 [Formula: see text] 0> orientation.
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