Alloy

About: Alloy is a research topic. Over the lifetime, 171884 publications have been published within this topic receiving 1719420 citations. The topic is also known as: alloys.

A development of Ti-based bulk metallic glass

Abstract: The thermal property, crystallization behavior, glass forming ability (GFA) and mechanical properties of Ti-based amorphous alloys were studied by using differential scanning calorimetry (DSC), X-ray diffractometry, transmission electron microscopy and compressive test. These alloys were developed systematically by considering atomic size and interaction parameters between constituting elements. Partial replacement of Cu by Be and Ti by Zr in Ti–Cu–Ni–Sn alloy improved the GFA. Fully amorphous rods, of diameter 2, 5 and 8 mm, could be fabricated by injection casting Ti 50 Cu 25 Ni 15 Sn 3 Be 7 , Ti 45 Cu 25 Ni 15 Sn 3 Be 7 Zr 5 and Ti 40 Zr 25 Ni 8 Cu 9 Be 18 alloys, respectively. The T rg (= T g / T l ) and γ (= T x /( T g + T l )) parameter shows a relatively good agreement with the maximum diameter of bulk glass, while Δ T x has poor relationship with the GFA of alloys. The bulk amorphous alloys exhibit high compressive strength of approximately 2500 MPa with good ductility.

Effects of Selective Laser Melting additive manufacturing parameters of Inconel 718 on porosity, microstructure and mechanical properties

Abstract: The effect of SLM parameters on porosity, microstructure and mechanical properties is studied. To this purpose, the Selective Laser Melting (SLM) technology is applied to manufacture Inconel 718 specimens. The material, the manufacturing process, the Hot Isostatic Pressure (HIP), heat treatment, observation procedures and characterisation of mechanical properties are presented. A columnar-dendritic microstructure was observed on all the SLM specimens and a Volumetric Energy Density (VED) effect on the latter was also noted. The rate of porosity varies in relation to the VED and is considerably reduced after HIP. The heat treatment erases the dendritic microstructure, significantly enhances microhardness and confers on the alloy tensile mechanical properties comparable to forged Inconel 718.

Alloy Clusters: Precise Synthesis and Mixing Effects

Abstract: ConspectusMetal alloys exhibit functionalities unlike those of single metals. Such alloying has drawn considerable research interest, particularly for nanoscale particles (metal clusters/nanoparticles), from the viewpoint of creating new functional nanomaterials. In gas phase cluster research, generated alloy clusters can be spatially separated with atomic precision in vacuum. Thus, the influences of increases or decreases in each element on the overall electronic structure of the cluster can be elucidated. However, to further understand the related mixing and synergistic effects, alloy clusters need to be produced on a large scale and characterized by various techniques. Because alloy clusters protected by thiolate (SR) can be synthesized by chemical methods and are stable in both solution and the solid state, these clusters are ideal study materials to better understand the mixing and synergistic effects. Moreover, the alloy clusters thus created have potential applications as functional materials. Ther...

Initial corrosion observed on the atomic scale

Abstract: Corrosion destroys more than three per cent of the world's GDP. Recently, the electrochemical decomposition of metal alloys has been more productively harnessed to produce porous materials with diverse technological potential. High-resolution insight into structure formation during electrocorrosion is a prerequisite for an atomistic understanding and control of such electrochemical surface processes. Here we report atomic-scale observations of the initial stages of corrosion of a Cu3Au111 single crystal alloy within a sulphuric acid solution. We monitor, by in situ X-ray diffraction with picometre-scale resolution, the structure and chemical composition of the electrolyte/alloy interface as the material decomposes. We reveal the microscopic structural changes associated with a general passivation phenomenon of which the origin has been hitherto unclear. We observe the formation of a gold-enriched single-crystal layer that is two to three monolayers thick, and has an unexpected inverted (CBA-) stacking sequence. At higher potentials, we find that this protective passivation layer dewets and pure gold islands are formed; such structures form the templates for the growth of nanoporous metals. Our experiments are carried out on a model single-crystal system. However, the insights should equally apply within a crystalline grain of an associated polycrystalline electrode fabricated from many other alloys exhibiting a large difference in the standard potential of their constituents, such as stainless steel (see ref. 5 for example) or alloys used for marine applications, such as CuZn or CuAl.