Journal of Alloys and Compounds
About: Journal of Alloys and Compounds is an academic journal. The journal publishes majorly in the area(s): Microstructure & Alloy. It has an ISSN identifier of 0925-8388. Over the lifetime, 61954 publication(s) have been published receiving 1194899 citation(s).
18 Apr 2002-Journal of Alloys and Compounds
Abstract: Magnesium and its alloys have excellent physical and mechanical properties for a number of applications. In particular its high strength:weight ratio makes it an ideal metal for automotive and aerospace applications, where weight reduction is of significant concern. Unfortunately, magnesium and its alloys are highly susceptible to corrosion, particularly in salt-spray conditions. This has limited its use in the automotive and aerospace industries, where exposure to harsh service conditions is unavoidable. The simplest way to avoid corrosion is to coat the magnesium-based substrate to prevent contact with the environment. This review details the state of the art in coating and surface modification technologies, applied to magnesium based substrates for improved corrosion and wear resistance. The topics covered include electrochemical plating, conversion coatings, anodizing, gas-phase deposition processes, laser surface alloying/cladding and organic coatings.
20 May 1997-Journal of Alloys and Compounds
Abstract: New reversible hydrogen storage systems are proposed, based on catalyzed reactions (Eqs. 4–6). The catalytic acceleration of the reactions in both directions is achieved by doping alkali metal aluminium hydrides with a few mol% of selected Ti compounds. The PCI diagrams of the Ti catalyzed systems show an absence of hysteresis and nearly horizontal pressure plateaus. The PCI of the NaAlH4 system reveals two temperature-dependent pressure plateaus, corresponding to the two-step reversible dissociation of NaAlH4. The PCI of the Na3AlH6 system shows only one pressure plateau; the latter can be lowered by partial substitution of Na by Li. In cyclic tests, reversible H2 capacities of 4.2–3.1 and 2.7–2.1 wt% H have been achieved.
29 Jun 1999-Journal of Alloys and Compounds
Abstract: The hydrogen storage properties of MgH 2 are significantly enhanced by a proper engineering of the microstructure and surface. Magnesium powders are produced in a nanocrystalline form, which gives remarkable improvement of absorption/desorption kinetics. Ball milling, which is used for fabrication of nanocrystalline magnesium, improves both the morphology of the powders and the surface activity for hydrogenation. The hydriding properties are further enhanced by catalysis through nano-particles of Pd located on magnesium surface. Nanocrystalline magnesium with such a catalyst exhibits an outstanding hydrogenation performance: very fast kinetics, operation at lower temperatures than conventional magnesium and no need for activation.
15 Nov 2012-Journal of Alloys and Compounds
Abstract: The present work shows that optimization of mechanical properties via heat treatment of parts produced by Selective Laser Melting (SLM) is profoundly different compared to conventionally processed Ti6Al4V. In order to obtain optimal mechanical properties, specific treatments are necessary due to the specific microstructure resulting from the SLM process. SLM is an additive manufacturing technique through which components are built by selectively melting powder layers with a focused laser beam. The process is characterized by short laser-powder interaction times and localized high heat input, which leads to steep thermal gradients, rapid solidification and fast cooling. In this research, the effect of several heat treatments on the microstructure and mechanical properties of Ti6Al4V processed by SLM is studied. A comparison is made with the effect of these treatments on hot forged and subsequently mill annealed Ti6Al4V with an original equiaxed microstructure. For SLM produced parts, the original martensite α′ phase is converted to a lamellar mixture of α and β for heat treating temperatures below the β-transus (995 °C), but features of the original microstructure are maintained. Treated above the β-transus, extensive grain growth occurs and large β grains are formed which transform to lamellar α + β upon cooling. Post treating at 850 °C for 2 h, followed by furnace cooling increased the ductility of SLM parts to 12.84 ± 1.36%, compared to 7.36 ± 1.32% for as-built parts.
15 Nov 1999-Journal of Alloys and Compounds
Abstract: Intensive mechanical milling was used to make MgH2–Tm (Tm=3d-transition elements Ti, V, Mn, Fe, Ni) nanocomposite powders. The hydrogen storage properties of these composite powders were evaluated. The five 3d-elements Ti, V, Mn, Fe and Ni showed different catalytic effects on the reaction kinetics of Mg–H system. Desorption was most rapid for MgH2–V, followed by MgH2–Ti, MgH2–Fe, MgH2–Ni and MgH2–Mn at low temperatures. The composites containing Ti exhibited the most rapid absorption kinetics, followed in order by Mg–V, Mg–Fe, Mg–Mn and Mg–Ni. Formation enthalpy and entropy of magnesium hydride were not altered by milling with transition metals, while the activation energy of desorption for magnesium hydride was reduced drastically.