The influence of stacking fault energy on the mechanical properties of nanostructured Cu and Cu–Al alloys processed by high-pressure torsion

Ultrafine-Grained Precipitation Hardened Copper Alloys by Swaging or Accumulative Roll Bonding

“…By finely spaced twinning a very fine grain size can be achieved after swaging leading to a hardness of more than 420 HV (which corresponds to tensile strengths higher than 1300 MPa). Figure 15 shows the refinement of the microstructure by twinning in CuAl5.8Si2 (estimated stacking fault energy around 6 mJ/m² or lower [20,21]) with increasing logarithmic deformation degree during swaging. However, CuAl5.8Si2 is non-age hardenable, therefore there are no precipitates stabilizing the grain boundaries during thermal exposure.…”

Improved Fatigue Strengths of Nanocrystalline Cu and Cu–Al Alloys

“…[15,16] As well known, severe plastic deformation (SPD) processes remarkably affect the formation of nanostructures and corresponding mechanical properties. [17,18] Compared with ECAP, high-pressure torsion (HPT), another popular SPD technique, can produce remarkably finer grains and a higher fraction of high-angle grain boundaries (GBs) and then harvest higher tensile strengths. [18,19] This indicates that the fatigue strengths of the NC materials processed by ECAP may be further escalated when prepared by HPT.…”

“…[17,18] Compared with ECAP, high-pressure torsion (HPT), another popular SPD technique, can produce remarkably finer grains and a higher fraction of high-angle grain boundaries (GBs) and then harvest higher tensile strengths. [18,19] This indicates that the fatigue strengths of the NC materials processed by ECAP may be further escalated when prepared by HPT. However, for the high-strength materials, the increase in their fatigue limits is extremely difficult and the fatigue strengths may remain constant or even decrease with a further increase in the tensile strengths, while the detailed mechanisms are still mysterious.…”

“…[18,21] In order to be suitable for fatigue experiments, disks for HPT processing were shaped with a diameter of 30 mm and a thickness of 2.5 mm ( Figure S1). These disks were processed using HPT facilities at the Erich Schmid Institute, Austrian Academy of Science, Austria, through five revolutions under an imposed pressure of 5.0 GPa at room temperature (RT) under quasi-constrained conditions.…”

Effect of the stacking fault energy on the mechanical properties of pure Cu and Cu-Al alloys subjected to severe plastic deformation

“…In [15] it was shown that in the Cu-Al alloys subjected to SPD by high pressure torsion, implemented at room temperature (RT), SFE plays an important role in the deformation process, since the strength of the alloy increases with decreasing SFE, and uniform elongation is also increased, with the exception of the alloys containing the lowest SFE (16 wt.% Al), where the uniform elongation is reduced. It was concluded that there is an optimum SFE (5 wt.% Al) to achieve the maximum uniform elongation in the Cu-Al alloys after HPT processing.…”