Microscopic mechanisms contributing to the synchronous improvement of strength and plasticity (SISP) for TWIP copper alloys

Abstract

In this study, the concept of “twinning induced plasticity (TWIP) alloys” is broadened, and the underlying intrinsic microscopic mechanisms of the general TWIP effect are intensively explored. For the first aspect, “TWIP copper alloys” was proposed following the concept of “TWIP steels”, as they share essentially the same strengthening and toughening mechanisms. For the second aspect, three intrinsic features of twinning: i.e. “dynamic development”, “planarity”, as well as “orientation selectivity” were derived from the detailed exploration of the deformation behavior in TWIP copper alloys. These features can be considered the microscopic essences of the general “TWIP effect”. Moreover, the effective cooperation between deformation twinning and dislocation slipping in TWIP copper alloys leads to a desirable tendency: the synchronous improvement of strength and plasticity (SISP). This breakthrough against the traditional trade-off relationship, achieved by the general “TWIP effect”, may provide useful strategies for designing high-performance engineering materials.

Deformation mechanisms to ameliorate the mechanical properties of novel TRIP/TWIP Co-Cr-Mo-(Cu) ultrafine eutectic alloys

“…The high magnification image and the fast Fourier transformation (FFT) pattern, shown in Fig. 6(b and c), reveal the formation of deformation twins and ε-Co phase at the γ-Co lamellae, which are generated by a strain-induced phase transformation (SIPT)313233. These ε-Co precipitates are located near the deformation twins situated at the γ-Co lamellae.…”

“…The inverse FFT images clearly display the deformation twins in the γ-Co lamellae. Generally, a strain-induced γ → ε phase transformation is commonly observed for polycrystalline cobalt alloys and γ-Co with low stacking fault energy facilitates twinning upon deformation33. Deformation twins have been also found in the various types of f.c.c.…”

The synchronous improvement of strength and plasticity (SISP) in new Ni-Co based disc superalloys by controling stacking fault energy

“…Under tensile deformation, wavy slip and dislocation cell are prevailing in pure Cu, while planar slip and deformation twinning will be activated in the alloyed Cu with lower SFE 18 , 19 . It has been demonstrated that this kind of DTs induced by quasi-static deformation cannot only improves the strength, but also enhances the plasticity, creating a unique effect of synchronous improvement of strength and plasticity in Cu-Al alloys 26 . The underlying mechanisms responsible for the SISP are well analyzed on the basis of the intrinsic features of DT and its critical role in the plastic deformation 26 .…”

Ductility Sensitivity to Stacking Fault Energy and Grain Size in Cu–Al Alloys

“…[1,10] In parallel, recent studies show that the face-centered cubic (FCC) alloys with low stacking fault energy (SFE) draw good balance of strength and ductility. [6,[11][12][13] In FCC materials, it is known that SFE can affect the deformation mechanisms significantly. [14][15][16] When the SFE is high, dislocation slip in the wavy mode dominates the plastic deformation.…”

“…Though tensile strength and ductility are readily improved in FCC metallic materials with decreasing the SFE, [6,[11][12][13]] the ductility cannot be enhanced monotonically as shown in Figure 1(e). Thus the ductility sensitivity to the SFE and grain size was summarized and shown in Figure 4 in both the fine-grained regime and the coarse-grained regime.…”