Designing (Ultra)Fine-Grained High-Entropy Alloys by Spark Plasma Sintering and Equal-Channel Angular Pressing

Rymer, L.-M.; Lindner, T.; Frint, P.; Löbel, M.; Lampke, T.

doi:10.3390/cryst10121157

Designing (Ultra)Fine-Grained High-Entropy Alloys by Spark Plasma Sintering and Equal-Channel Angular Pressing (bibtex)

by L.-M. Rymer, T. Lindner, P. Frint, M. Löbel, T. Lampke

Abstract:

Single-phase, face-centered cubic (FCC) high-entropy alloys (HEA) are promising materials for future applications. In order to improve the mechanical properties, especially the tensile strength of these materials, this study focuses on the combination of spark plasma sintering (SPS) and equal-channel angular pressing (ECAP). The initial fine-grained microstructure produced by SPS is further refined by ECAP in a 90°-die. Optical microscopy and electron backscatter diffraction (EBSD) confirm this considerable grain refinement, leads to a grain size below 1 µm after 1 ECAP pass. An alternating arrangement of fine-grained areas and much coarser regions, aligned under an angle of approximately 27°, is found. Moreover, a first microstructural investigation of the twin structure is conducted. The mechanical behavior was investigated by hardness measurements and tensile testing. Both the hardness and tensile strength are remarkably increased after ECAP. In contrast, the uniform elongation and elongation at fracture are significantly reduced due to the strengthening mechanisms of strain hardening and grain refinement. It is concluded that the combination of SPS and ECAP is an attractive approach for designing (ultra)fine-grained HEAs with superior properties. The investigated techniques could be applied to understand the underlying microstructural mechanisms.

Reference:

Rymer, L.-M., Lindner, T., Frint, P., Löbel, M., Lampke, T.: Designing (Ultra)Fine-Grained High-Entropy Alloys by Spark Plasma Sintering and Equal-Channel Angular Pressing, Crystals 10, 1157, 2020.

Bibtex Entry:

@Article{Rymer2020,
  author    = {Rymer, L.-M. and Lindner, T. and Frint, P. and Löbel, M. and Lampke, T.},
  journal   = {Crystals},
  title     = {Designing (Ultra)Fine-Grained High-Entropy Alloys by Spark Plasma Sintering and Equal-Channel Angular Pressing},
  year      = {2020},
  month     = {dec},
  number    = {12},
  pages     = {1157},
  volume    = {10},
  abstract  = {Single-phase, face-centered cubic (FCC) high-entropy alloys (HEA) are promising materials for future applications. In order to improve the mechanical properties, especially the tensile strength of these materials, this study focuses on the combination of spark plasma sintering (SPS) and equal-channel angular pressing (ECAP). The initial fine-grained microstructure produced by SPS is further refined by ECAP in a 90°-die. Optical microscopy and electron backscatter diffraction (EBSD) confirm this considerable grain refinement, leads to a grain size below 1 µm after 1 ECAP pass. An alternating arrangement of fine-grained areas and much coarser regions, aligned under an angle of approximately 27°, is found. Moreover, a first microstructural investigation of the twin structure is conducted. The mechanical behavior was investigated by hardness measurements and tensile testing. Both the hardness and tensile strength are remarkably increased after ECAP. In contrast, the uniform elongation and elongation at fracture are significantly reduced due to the strengthening mechanisms of strain hardening and grain refinement. It is concluded that the combination of SPS and ECAP is an attractive approach for designing (ultra)fine-grained HEAs with superior properties. The investigated techniques could be applied to understand the underlying microstructural mechanisms.},
  doi       = {10.3390/cryst10121157},
  publisher = {{MDPI} {AG}},
}