Details

Autor(en) / Beteiligte

• Zhao, Y. F
• Zhang, J. Y
• Wang, Y. Q
• Wu, K
• Liu, G
• Sun, J

Titel

Unusual plastic deformation behavior of nanotwinned Cu/high entropy alloy FeCoCrNi nanolaminates

Ist Teil von

• Nanoscale, 2019-06, Vol.11 (23), p.1134-1135

Ort / Verlag

England: Royal Society of Chemistry

Erscheinungsjahr

2019

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Compared with coarse-grained FeCoCrNi-based high entropy alloys (HEAs), their nanocrystalline (NC) siblings with ultra-high strength often suffer from notably reduced deformability. Here, to enhance the deformability of these NC HEAs without losing their high strength, we design equal layered nanotwinned (NT) Cu/HEA (HEA = FeCoCrNi) crystalline/crystalline nanolaminates (C/CNLs) with coherent crystalline/crystalline interfaces (CCIs). In contrast to the tenet that in conventional bimetal C/CNLs, the soft/ductile phase plays the dominant major role, we discover that in NT Cu/HEA C/CNLs, the hard HEA phase unusually makes more contribution to the plastic deformation. The underlying reason is that the soft NT Cu layers without dislocation pile-up serve as the dislocation donator and export abundant dislocations that transmit across the coherent CCIs into the hard HEA accepter, and thus trigger their great deformability. The size-dependent hardness was explained based on dislocation-based models considering the stability of extremely small nanotwins with thickness less than ∼10 nm. These findings provide a new pathway to achieve great deformability of strong alloys with high lattice friction stresses in ultra-strong metallic composites: control the size of NT soft phases to suppress dislocation pile-up in conjunction with coherent CCIs to facilitate continuity of dislocation slip. Contrary to the popular belief that the soft phase in bimetal multilayers plays the dominant role in plastic deformation, the hard FeCoCrNi high entropy alloys (HEA) phase makes more contribution to the deformation of Cu/HEA nanolaminates.