Selective laser melting (SLM) process was used to prepare the nanocrystalline titanium carbide (TiC)-reinforced Inconel 718 matrix bulk-form nanocomposites in the present study. An in-depth relationship between SLM process, microstructures, properties, and metallurgical mechanisms was established. The insufficient laser energy density (η) input limited the densification response of shaped parts due to the formation of either larger-sized pore chains or interlayer micropores. The densification of SLM-processed part increased to a near-full level as the applied η was properly settled. The TiC reinforcements generally experienced successive changes from severely agglomerated in a polygon shape to the uniformly distributed with smoothened and refined structures on increasing the applied η, while the columnar dendrite matrix exhibited strong epitaxial growth characteristic concurrently. The optimally prepared fully dense part achieved a high microhardness with a mean value of 419 HV0.2, a considerably low friction coefficient of 0.29, and attendant reduced wear rate of 2.69 × 10−4 mm3/N m in dry sliding wear tests. The improved densification response, SLM-inherent nonequilibrium metallurgical mechanisms with resultant uniformly dispersed reinforcement microstructures, and elevated microhardness were believed to be responsible for the enhancement of wear performance.

High Speed Sintering (HSS) is a novel additive manufacturing technology which currently uses Nylon 12 as the standard feedstock material. To expand the number of processable materials, the preferred characteristics of polymeric powder as a feedstock powder are presented, appropriate materials identified, parts made, and mechanical properties measured. Two commercially available laser sintering (LS) grade powders previously untested for HSS were selected, DuraForm® HST10 and ALM TPE 210-S. Tensile test specimens were manufactured using each material and mechanical properties analyzed and compared to the manufacturers' specification for LS. Tensile test specimens built using DuraForm® PA show higher tensile strength and elongation at break than LS whereas DuraForm® HST10 shows somewhat reduced tensile strength but slightly increased elongation at break. ALM TPE 210-S shows elongation at break of more than double that of LS demonstrating the capability of HSS to process viscous materials. The results indicate that HSS is capable of processing LS grade polymeric powders and may extend beyond.

The effects of magnetic field on the austenite formation and grain size were studied by applying high magnetic field during the different stages. Optical microscopy and scanning electron microscopy were used to characterize the microstructure evolution for the samples treated without and with magnetic field. Magnetic field dramatically retards the austenite formation kinetics including pearlite to austenite transformation and cementite dissolution. The austenite grain size is enlarged by the magnetic field applied during austenite formation and not affected by the magnetic field applied only during austenite grain coarsening. The austenite treated with magnetic field during the whole austenitization process also has a larger grain size. The changes in austenite formation kinetics and grain size are related to lower nucleation rate of austenite caused by magnetic field.

Au nanoparticles (Au NPs) have attracted much interest owing to their unique optical properties. In this paper, a facile process has been successfully developed to synthesize the SiO2/Au hybrid microspheres with a diameter of 200 nm via the galvanic replacement of SiO2/Ag hybrid microspheres and chlorauric acid (HAuCl4) solution. The as-prepared products were investigated by x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM, JEOL-6700F), and transmission electron microscopy (TEM, JEOL 3010), respectively. As expected, the as-prepared SiO2/Au hybrid microspheres show strong chemical stability and superior catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The SiO2/Au hybrid microspheres would be found widely used in wastewater treatment, catalytic reaction, bacteriostatic and bactericidal applications.

In situ transmission electron microscopy (TEM) analysis shows that submicrometer grains formed by ultrasonic impact treatment (UIT) of sensitized 5456-H116 Al–Mg alloy products are thermally stable up to ∼300 °C which is consistent with previous research on annealing of heavily deformed Al–Mg. Grain growth occurs above 300 °C with significant growth at ∼400 °C. Grain growth continued upon heating to 450 °C; the grain size did not significantly increase when the temperature was held at 450 °C long term. In situ TEM revealed a duplex microstructure that was not fully recrystallized. The activation energy for grain growth was determined to be ∼32 kJ/mol. The submicrometer grains produced by UIT offer improved resistance to fatigue and corrosion. The majority of sensitized 5456-H116 failures are sensitive to the material's surface properties and operational service temperature; the stability of the submicrometer grains in the UIT Al–Mg makes them more stable in practical operations where increase in the material temperature is an issue.

Laser sintering allows producing end-use parts directly from computer files with no tooling required. For these parts to be used in industrial applications, their mechanical properties throughout in-service applications must be examined. The aim of this article is to provide an understanding of the dynamic performance of laser-sintered Nylon 12 parts. To investigate the viscoelastic properties of the material, dynamic thermal mechanical analysis has been performed in different frequencies and temperatures. Tension–tension cyclic behavior of samples has been studied and creep is shown to have a great impact in such behavior in addition to fatigue. Stress relaxation plots are provided and compared with the cyclic loading plots validating the fact that samples experience a combination of creep and fatigue in tension–tension loading. Hysteresis loops indicate brittle crack propagation in the samples experiencing fatigue.