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The trade‐off relation between strength and plasticity is the bottleneck that limits the development of high‐strength and high‐plasticity Al–Cu alloys. Inspired from the influence of precipitate shape on the work‐hardening behavior of Al–Cu alloys, an Al–Cu–Zr–Sc alloy containing a mixed microstructure of spherical‐shaped Al3(Zr, Sc) phases and disk‐shaped θ′ phases is successfully designed and fabricated. Surprisingly, it is found that the strength and plasticity of the Al–Cu–Zr–Sc alloy are synchronously improved compared to the Al–Cu alloy with only disk‐shaped θ′ phases. The introduction of spherical‐shaped Al3(Zr, Sc) phases can increase the yield strength without sacrificing the work‐hardening ability of the Al–Cu–Zr–Sc alloy, which is mainly attributed to the extremely small strain‐hardening exponent of the Al alloy with spherical‐shaped precipitates. Besides, the predicted strength–elongation relation of the Al–Cu alloy is established based on the exponential strain‐hardening model. [ABSTRACT FROM AUTHOR]

In the process of electric power transmission, the defects in the copper wire interact with the electrons which results in a thermal effect, accordingly, causing the changes of microstructure and properties of the copper wire. Herein, the evolution of microstructure, strength, and electrical conductivity of the oxygen‐free copper wires annealed at different temperatures is investigated. In addition, the effects of various microstructures on strength and electrical conductivity are quantitatively revealed. In the low‐temperature region (80–150 °C), dislocation recovery is the main reason for the decrease in strength; while, the increase in electrical conductivity is mainly due to the decrease in dislocation density and the transformation of grain boundary from nonequilibrium state to equilibrium state. In the high‐temperature region (above 210 °C), the strength loss is mainly related to the increasing recrystallized grain size and the disappearance of dislocations in the recrystallized region. The increase in electrical conductivity is mainly attributed to the significant decrease in grain boundary density and the further recovery of dislocations. [ABSTRACT FROM AUTHOR]

During the selective laser melting (SLM) process of Ti6Al4V, a special structure can be formed with columnar prior β grains along the building direction and fully martensitic α′ within the β grain. To investigate the influence of such special structure on the fatigue crack growth (FCG) rate, Ti6Al4V specimens fabricated by SLM were heat‐treated at two different temperatures in this study. The columnar grains were retained, and the martensite was decomposed when heat‐treated below the β transus. It is found that all the SLM features were removed when heat‐treated above the β transus. FCG rate tests were subsequently performed at room temperature, and it was found that the prior β grains affected the macroscopic fracture morphology, but there was no discernible influence on the FCG rate. The morphology of the α phase affected the crack growth path and the FCG rate. Changes in the strength‐toughness relationship induced by heat treatment can help understand the decrease in the FCG rate. Highlights: Heat treatments at two temperatures were used to eliminate SLM features.The morphology of the α phase affected the fatigue crack growth path and rate.The strength‐toughness relationship can help to understand the variation of FCG rate. [ABSTRACT FROM AUTHOR]

A simple exponential strain hardening model (ESH) has been developed in the framework of the Kocks-Mecking-Estrin formalism with a new microstructure-based parameter that accounts for the effect of yield strength. The relevant parameters reflecting the effect of the composition (or dislocation annihilation distance) and the microstructure type (or strengthening technology) are comprehensively analyzed. The application scope of the model is then briefly discussed, and several significant advantages are enumerated including the clear derivation processes and the explicit physical meaning of the various parameters. Finally, the ESH model is verified extensively by systematic tensile tests on six groups of Cu-Al alloys having more than one hundred microstructural states. In addition, significant and quantitative revelations of strength and uniform elongation for ductile metals are elaborated in the following manuscript. The present ESH model is of significant theoretical value in providing a detailed understanding of the tensile performance of metallic materials. [Display omitted] [ABSTRACT FROM AUTHOR]

An exponential strain-hardening (ESH) model for single phase metals was established and well verified by systematic experiments on Cu-Al alloys in an earlier study. In this report, several additional significant revelations will be documented for the tensile behaviors of several typical metals. Firstly, a unified interpretation of the well-known five strain-hardening stages is developed by correlating the characteristics of each stage with the parameter n that relates to the dislocation annihilation behavior. Secondly, quantitative relationships among the yield strength (YS), ultimate tensile strength (UTS) and uniform elongation (UE) are established and verified using the tensile experimental results for Cu-Al alloys. Thirdly, the two general principles of the synchronous improvement of strength and uniform elongation (SISUE) effect, such as the composition adjustment and microstructure optimization, are quantitatively revealed by the composition parameter n and a microstructure type parameter η. Two typical trends of the true UTS-UE curves and two kinds of characteristic strengths are quantitatively revealed and confirmed by the relevant experimental data. Finally, a prediction model of tensile properties is proposed and a corresponding procedure is displayed, which is further verified by the tensile experimental results for Cu-Al alloys. These applications further support the validity and significance of the ESH model. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights • Flower-like AgNPs are facilely synthesized with two-step wet-chemical method. • Effect of gum arabic and HNO 3 on morphology of AgNPs is intensively investigated. • The growth mechanism of AgNPs is analyzed. Abstract Flower-like silver nanoparticles (F-AgNPs) are facilely synthesized with two-step wet-chemical method. In the first step, ho leaf extracts reduce AgNO 3 to form spherical AgNPs. In the second step, F-AgNPs are synthesized from spherical particles. The effect of gum arabic and HNO 3 on morphology of F-AgNPs is intensively investigated. The reduction and oxidation provide a trade-off between aggregation and detachment of Ag atoms on the surface, while the structure-directing agent boosts preferential growth, contributing to formation of F-AgNPs with different shapes. Our results pave an alternative way for synthesizing AgNPs with specific shapes and advancing applications. [ABSTRACT FROM AUTHOR]