The effects of different Gd additions on wear behavior of the T6 heat treated Mg–xGd–3Y–0.5Zr alloys were investigated. The wear tests were carried out using a Ball-on-flat type wear apparatus against an AISI 52100 type bearing steel ball counterface in the load range of 3–15 N, sliding speed range of 0.03–0.18 m/s, temperature range of 25–200 °C and at a constant sliding distance of 400 m. The results showed that the wear rate of the tested alloys increased with increasing sliding load. By increasing the wear temperature to 200 °C, the wear rate of the Mg–6Gd–3Y–0.5Zr alloy decreased by about 24%. At higher wear speeds, wear resistance of the alloys increased due to the formation of stable oxide layers on the worn surfaces. The alloy containing 12 wt% Gd exhibited higher wear resistance compared with the alloys containing lower Gd contents under the same conditions.

The effect of electropulsing assisted ultrasonic surface modification (EUSM) on microstructure and surface properties of S50C steel welded components is investigated. Compared with conventional ultrasonic surface modification (USM) process, EUSM process achieves significant improvements in microstructure, including deeper strengthened layers and gradient microstructure on the surface. The EUSM-induced microstructure results in higher levels of surface compressive residual stress and greater surface microhardness and its effective depth. Conventional USM process is inevitably accompanied by some plastic damages, such as pit and crack defects. The damages, however, can be eliminated to some extent during the EUSM process. These enhancements may be attributed to the thermal and athermal effects caused by electropulsing treatment, which accelerates the mobility of dislocations in the dynamic recrystallization process.

The tin–bismuth eutectic alloy possesses anomalous physicochemical properties that are dependent on temperature. This paper reports the interfacial reaction and growth behavior of the intermetallic compound (IMC) layer during the dissolution of solid copper in liquid eutectic tin–bismuth at 673–823 K under the influence of the structural transition of liquid eutectic tin–bismuth. The structural transition markedly affected the dissolution rate constant of solid copper and the growth rate of the IMCs. Correspondingly, the application of the liquid structural transition significantly decreased the activation energy of dissolution and increased the apparent activation energy for IMC growth. Moreover, two major roles of elemental Bi on the formation and growth of the IMCs were suggested.

Data mining has revolutionized sectors as diverse as pharmaceutical drug discovery, finance, medicine, and marketing, and has the potential to similarly advance materials science. In this paper, we describe advances in simulation-based materials databases, open-source software tools, and machine learning algorithms that are converging to create new opportunities for materials informatics. We discuss the data mining techniques of exploratory data analysis, clustering, linear models, kernel ridge regression, tree-based regression, and recommendation engines. We present these techniques in the context of several materials application areas, including compound prediction, Li-ion battery design, piezoelectric materials, photocatalysts, and thermoelectric materials. Finally, we demonstrate how new data and tools are making it easier and more accessible than ever to perform data mining through a new analysis that learns trends in the valence and conduction band character of compounds in the Materials Project database using data on over 2500 compounds.

As a relatively new class of hierarchically structured materials, nanotwinned (NT) metals exhibit an exceptional combination of high strength, good ductility, large fracture toughness, remarkable fatigue resistance, and creep stability. This article reviews current studies on fracture, fatigue, and creep of NT metals, with an emphasis on the fundamental deformation and failure mechanisms. We focus on the complex interactions among cracks, dislocations, and twin boundaries, the influence of microstructure, twin size, and twinning/detwinning on damage evolution, and the contribution of nanoscale twins to fatigue and creep under indentation and irradiation conditions. The article also includes critical discussions on the effects of twin thickness and grain size on the fracture toughness, fatigue resistance, and creep stability of NT metals.

Thick coatings of tetrahedral amorphous carbon (ta-C) have great existing and potential commercial importance for components such as automobile accessories. We confirmed the feasibility of depositing thick ta-C coating on Si wafer, WC, stainless steel (STS), and Al alloy substrates by a home-made filtered cathode vacuum arc. A ta-C coating of 800 nm thickness was successfully deposited over 20 min continuous coating. Interestingly, coatings with thicknesses exceeding 1 μm were easily delaminated by thermal and internal stress effects when the coating time exceeded 20 min. Varying the bias (0 V ↔ 500 V) was highly effective in controlling the internal stress relaxation of the ta-C. This method showed significant improvements in the stress relaxation of the ta-C coatings. By applying multicycle coating, the thickness and hardness of the ta-C coating could reach 9.3 μm and 45 GPa, respectively, at a coating speed of 3.0 μm/h on a fixed substrate.

This article focuses on in situ transmission electron microscope (TEM) characterization to explore twins in face-centered-cubic and body-centered-cubic monolithic metals, and their impact on the overall mechanical performance. Taking advantage of simultaneous nanomechanical deformation and nanoscale imaging using versatile in situ TEM tools, direct correlation of these unique microscopic defects with macroscopic mechanical performance becomes possible. This article summarizes recent evidence to support the mechanisms related to strengthening and plasticity in metals, including nanotwinned Cu, Ni, Al, Au, and others in bulk, thin film, and nanowire forms.