One-dimensional noble metal nanostructures are important components in modern nanoscience and nanotechnology due to their unique optical, electrical, mechanical, and thermal properties. However, their cost and scalability may become a major bottleneck for real-world applications. Copper, being an earth-abundant metallic element, is an ideal candidate for commercial applications. It is critical to develop technologies to produce 1D copper nanostructures with high monodispersity, stability and oxygen-resistance for future low-cost nano-enabled materials and devices. This article covers comprehensively the current progress in 1D copper nanostructures, most predominantly nanorods and nanowires. First, various synthetic methodologies developed so far to generate 1D copper nanostructures are thoroughly described; the methodologies are in conjunction with the discussion of microscopic, spectrophotometric, crystallographic and morphological characterizations. Next, striking electrical, optical, mechanical and thermal properties of 1D copper nanostructures are highlighted. Additionally, the emerging applications of 1D copper nanostructures in flexible electronics, transparent electrodes, low cost solar cells, field emission devices are covered, amongst others. Finally, there is a brief discussion of the remaining challenges and opportunities.

1D copper nanostructures: progress, challenges and opportunities.

Metallurgical and mechanical characterization of stir cast AA6061-T6–AlNp composite

Hot deformation behavior of AISI 410 martensitic stainless steel was investigated by conducting hot compression tests at the temperatures of 900–1150 °C and the strain rates of 0.001–1 s −1 . The relation between the flow stress and Zener–Hollomon parameter was successfully analyzed via the hyperbolic sine function under the whole range of deformation condition. Therefore, the value of apparent activation energy and the empirical materials constants of A and n were determined. The values of both strain and stress of peak and steady state flow were related to Zener–Hollomon parameter and pertaining relations were proposed. On the basis of dynamic materials model the power dissipation map and the instability map were developed. The processing map was obtained by superimposition of the power dissipation and the instability maps and the regions having the lowest strain rate sensitivity added for more clarification of low and high workability regions. Optical microscopy observations of prior austenite grains showed that dynamic recrystallization grain size had an adverse relation with Zener–Hollomon parameter. According to grain size measurements, the best relation between dynamic recrystallization grain size and Zener–Hollomon parameter was proposed.

Characterization of hot deformation behavior of 410 martensitic stainless steel using constitutive equations and processing maps

A transient three dimensional model for describing the thermo-capillary convection and migration behavior and the resultant distribution state of reinforcing particles during selective laser melting of AlN/AlSi10Mg is proposed. The powder–solid transformation, temperature dependent physical properties and interaction between the reinforcement and the melt are taken into account. The effect of the laser energy per unit length (LEPUL) on the molten pool dynamics, cooling rate and the resultant sizes and distribution state of AlN reinforcement has been investigated. It shows that the thermo-capillary convection pattern changes from inward flow pattern to outward one, due to the appearance of the oxidation in molten pool. Therefore, the morphology of the top surface undergoes a continuous variation from the balling phenomenon, to the discontinuous tracks and finally to the formation of a flat and dense one. Meanwhile, both the clockwise and counterclockwise convection patterns are produced in the molten pool, caused by the interaction of reinforcing particles and the melt. An increase in LEPUL will significantly intensify the thermo-capillary convection whereas result in a decrease in the cooling rate of the molten pool. As LEPUL decreases from 1800 J/m to 450 J/m, the distribution state of AlN particles changes from the severe aggregation, then to the formation of partial aggregation and finally to the homogeneous distribution in the solidified matrix. The particle sizes of AlN reinforcement are experimentally acquired, which are in a good agreement with the results predicted by simulation.

Influence of thermodynamics within molten pool on migration and distribution state of reinforcement during selective laser melting of AlN/AlSi10Mg composites

https://hal.archives-ouvertes.fr/hal-01715082/document

The effect of the addition of alloying elements on carbide precipitation and mechanical properties in 5% chromium martensitic steels

The interfacial reaction products of the Al-Mg/TiC
 p
 composite fabricated by the pressureless infiltration method were analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). During the fabrication of composites, reaction products with various morphologies and sizes were formed in the A1 matrix as well as in the vicinity of the TiC particles by the interfacial reaction between the Al alloy and the TiC particles. From the EDS and selected-area diffraction pattern (SADP) analysis, Al4C3, Al18Ti2Mg3, Ti2AlC, Al3Ti, and TiAl could be identified to form as interfacial reaction products. Both the size and the amount of the reaction products were increased with increasing fabrication temperature as well as fabrication time. Coarse Al3Ti was barely observed in water-quenched composites, while it was observed at all fabrication temperatures (700 °C to 1000 °C) in furnace-cooled conditions.

https://link.springer.com/content/pdf/10.1007%2Fs11661-006-0052-8.pdf

Reaction products of Al/TiC composites fabricated by the pressureless infiltration technique

The secondary hardening and fracture behavior in P/M high speed steels of W–Mo–Cr–V(–Co) system has been investigated in terms of Co addition and austenitizing temperature. Austenitizing was conducted at 1100 and 1175 °C of relatively low and high temperatures, respectively. Tempering was performed in the range of 500–600 °C. Coarse primary carbides retained after heat treatment were V-rich MC and W–Mo-rich M6C types. Since the dissolution of W–Mo-rich M6C with relatively low stability was more promoted with increasing austenitizing temperature, the alloy content of the W and Mo in the matrix was enhanced. In turn, it gives a significant influence on the precipitation of fine secondary alloy carbides, that is, secondary hardening during tempering. The major secondary carbides were W–Mo–Cr-rich M2C type. The peak hardness was observed in the tempering range of 500–540 °C, depending on Co addition and austenitizing temperature. With an increase in austenitizing temperature, the aging deceleration was observed. This phenomenon may be attributed to the increased content of W and Mo in the matrix, both diffusing slowly in the matrix and inhibiting growth of M2C carbide, as compared to Cr. In addition, the aging acceleration occurred in the Co bearing alloy, promoting the precipitation of M2C carbides, as well as the overall increase in hardness. In general, the impact toughness was decreased with an increase in hardness. In addition, the impact toughness to hardness balance was lowered in the Co bearing alloy.

Influences of Co addition and austenitizing temperature on secondary hardening and impact fracture behavior in P/M high speed steels of W–Mo–Cr–V(–Co) system

The effects of alloying additions and austenitizing treatments on secondary hardening and fracture behavior of martensitic steels containing both Mo and W were investigated. The secondary hardening response and properties of these steels are dependent on the composition and distribution of the carbides formed during aging (tempering) of the martensite, as modified by alloying additions and austenitizing treatments. The precipitates responsible for secondary hardening are M2C carbides formed during the dissolution of the cementite (M3C). The Mo-W steel showed moderately strong secondary hardening and delayed overaging due to the combined effects of Mo and W. The addition of Cr removed secondary hardening by the stabilization of cementite, which inhibited the formation of M2C carbides. The elements Co and Ni, particularly in combination, strongly increased secondary hardening. Additions of Ni promoted the dissolution of cementite and provided carbon for the formation of M2C carbide, while Co increased the nucleation rate of M2C carbide. Fracture behavior is interpreted in terms of the presence of impurities and coarse cementite at the grain boundaries and the variation in matrix strength associated with the formation of M2C carbides. For the Mo-W-Cr-Co-Ni steel, the double-austenitizing at the relatively low temperatures of 899 to 816 °C accelerated the aging kinetics because the ratio of Cr/(Mo + W) increased in the matrix due to the presence of undissolved carbides containing considerably larger concentrations of (Mo + W). The undissolved carbides reduced the impact toughness for aging temperatures up to 510 °C, prior to the large decrease in hardness that occurred on aging at higher temperatures.

Effects of alloying additions and austenitizing treatments on secondary hardening and fracture behavior for martensitic steels containing both Mo and W

The purpose of this study was to analyze the effect of Co and Ni additions on secondary hardening and fracture behavior of the martensitic steels bearing W and Cr, where W exhibits a much weaker effect on the secondary hardening compared with Mo and Cr can contribute to an increase in toughness even though the Cr additions weaken the secondary hardening in Mo and W steels. The chemical compositions of the alloys used in this study are presented in Table 1. Impact specimens were austenitized in a flowing argon atmosphere at 1,200 C for 1 hour and then water- or oil-quenched. Austenitized specimens were aged in a neutral salt bath at 400 C and 650 C for 1 hour and then water-quenched. Fractography was conducted on fracture surfaces cut off the impact-tested samples, while samples for hardness measurements were obtained from a second cut 5 to 10 mm below the fracture surface. Hardness was measured using the Rockwell C scale (HRc), and average values of five readings are reported. In order to observe martensitic substructures (M{sub 2}C and M{sub 3}C carbides), thin foils were examined in a JEOL transmission electron microscope (TEM), operated at 120 kV. The variations in hardnessmore » for 6W, 3W-3Cr, 3W-3Cr-14Co, and 3W-3Cr-14Co-10Ni steels are shown.« less

K. B. Lee

Papers

Reaction products of Al/TiC composites fabricated by the pressureless infiltration technique

Influences of Co addition and austenitizing temperature on secondary hardening and impact fracture behavior in P/M high speed steels of W–Mo–Cr–V(–Co) system

Effects of alloying additions and austenitizing treatments on secondary hardening and fracture behavior for martensitic steels containing both Mo and W

Effects of Co and Ni on secondary hardening and fracture behavior of martensitic steels bearing W and Cr

A novel etchant for revealing the prior austenite grain boundaries and matrix information in high alloy steels