Fabricating metallic materials with ultrafine or nanoscale microstructure using the severe plastic deformation (SPD) technique has been shown as an effective strategy to significantly improve the overall performance of the materials. Compared with their coarse-grained counterparts, ultrafine-grained and nanostructured metals and alloys exhibit ultra-high strength and hardness, and superior wear and corrosion resistance. However, these improvements are typically achieved at the cost of a drastic decline in the ductility. This prohibits the use of SPD technique for the manufacture of many engineering components. The strength-ductility trade-off dilemma has partially eased in recent years since novel strategies were developed to produce materials with ‘gradient structure’ using surface mechanical treatments, such as the surface mechanical attrition treatment (SMAT) and the surface mechanical grinding treatment (SMGT). Materials with the gradient structure exhibit desirable properties
Abstract
High strength, ductile and wear-resistant alloys are required for engineering applications. This work reports a good combination of mechanical and tribological properties in (NiAl) (FeCr) Co high-entropy alloys (HEAs) via adjusting A2/B2 nano-coupled heterostructure. The A2/B2 heterostructure switches from weave to network structure by increasing x:y ratio from 1:1.3 to 1:1, and eventually forms an island structure when x:y ratio is 1.3:1. Concurrently, the grain boundary FCC phase transforms from continuous to discontinuous as its fraction decreases. The island-like A2/B2 heterostructure provides (NiAl) (FeCr)Co HEA a good compressive yield strength of 1.7 GPa and plasticity of 23.4%. Additionally, (NiAl) (FeCr)Co HEA has the promising wear-resistance from room temperature to 800 °C, ascribing to its excellent strength and the protective tribo-layer at high temperatures. x y (x+y)/2 1.3 1.15 1.3 1.15
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