Enhancing grain refinement efficiency and fading resistance of Al–B master alloys processed by equal channel angular pressing

The microstructural evolution and grain refinement of Cu-Al alloys with different stacking fault energies (SFEs) processed by equal-channel angular pressing (ECAP) were investigated. The grain refinement mechanism was gradually transformed from dislocation subdivision to twin fragmentation with tailoring the SFE of Cu-Al alloys. Concurrent with the transition of grain refinement mechanism, the grain size can be refined into from ultrafine region (1 m~100 nm) to the nanoscale (<100 nm) and then it is found that the minimum equilibrium grain size decreases in a roughly linear way with lowering the SFE. Moreover, in combination with the previous results, it is proposed that the formation of a uniform ultrafine microstructure can be formed more readily in the materials with high SFE due to their high recovery rate of dislocations and in the materials with low SFE due to the easy formation of a homogeneously-twinned microstructure.

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Mechanism of Grain Refinement during Equal-Channel Angular Pressing at Intermediate Temperature in an Al-Mg-Sc Alloy

Proceedings of the 6th International Conference on Recrystallization and Grain Growth (ReX&GG 2016) ◽

10.1007/978-3-319-48770-0_35 ◽

2016 ◽

pp. 239-244

Author(s):

Sergey Malopheyev ◽

Vladislav Kulitskiy ◽

Marat Gazizov ◽

Rustam Kaibyshev

Keyword(s):

Grain Refinement ◽

Equal Channel Angular Pressing ◽

Intermediate Temperature ◽

Angular Pressing

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

Crystals ◽

10.3390/cryst10121157 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1157

Author(s):

Lisa-Marie Rymer ◽

Thomas Lindner ◽

Philipp Frint ◽

Martin Löbel ◽

Thomas Lampke

Keyword(s):

Tensile Strength ◽

Grain Refinement ◽

Spark Plasma Sintering ◽

Equal Channel Angular Pressing ◽

High Entropy Alloys ◽

High Entropy ◽

Fine Grained ◽

Angular Pressing ◽

Plasma Sintering ◽

Spark Plasma

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.

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