Details

Autor(en) / Beteiligte

• Ding, Z.Y.
• He, Q.F.
• Wang, Q.
• Yang, Y.

Titel

Superb strength and high plasticity in laves phase rich eutectic medium-entropy-alloy nanocomposites

Ist Teil von

• International journal of plasticity, 2018-07, Vol.106, p.57-72

Ort / Verlag

New York: Elsevier Ltd

Erscheinungsjahr

2018

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Laves phase and laves-phase based conventional composites usually show extreme brittleness at room temperature due to poor fracture toughness. However, in this work, we design a FeCoNiNb0.5 medium-entropy-alloy nanocomposite which possesses a high volume fraction (>50%) of a cubic laves phase but shows superb strength and excellent malleability at room temperature. This high mechanical performance results from the formation of an in-situ nano-scale lamellar structure that joins the hard cubic laves phase and soft medium entropy face-centered cubic (FCC) phase through a semi-coherent interface. When the size of the lamellar structures is tuned below a critical value, this nanocomposite exhibits strong and sustainable strain hardening, leading to a fracture strain over 20% and fracture strength over 3.5 GPa in conventional compression. The mechanism for the unusual strain hardening in the laves-phase rich nanocomposite is explored afterwards with micromechanical experiments and theoretical modeling, which unveils a size-controlled transition in the plasticity mechanism from dislocation slip to twinning in the nano-scale laves phase. Our current work demonstrates that, through mixing a set of carefully selected elements, one can obtain high performance dual-phase eutectic nanostructures which are promising for structural applications. [Display omitted] •An eutectic medium-entropy-alloy nanocomposite containing over 50% C15 Laves phase was developed.•The nanocomposite exhibited superb strength and high plasticity at room temperature.•A dislocation based theoretical model was developed for the yielding of the nanocomposite.•The micro-scale deformation mechanisms of the nanocomposites were fully examined.•The size-controlled deformation mechanism in the nanocomposites was revealed.