Topic
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.
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TL;DR: These three different near-surface compositions (Pt-skin, Pt-skeleton, and pure polycrystalline Pt) all having pure-Pt outermost layers are found to have different electronic structures, which originates from different arrangements of subsurface atoms of the alloying component.
Abstract: The surface properties of PtM (M = Co, Ni, Fe) polycrystalline alloys are studied by utilizing Auger electron spectroscopy, low energy ion scattering spectroscopy, and ultraviolet photoemission spectroscopy. For each alloy initial surface characterization was done in an ultrahigh vacuum (UHV) system, and depending on preparation procedure it was possible to form surfaces with two different compositions. Due to surface segregation thermodynamics, annealed alloy surfaces form the outermost Pt-skin surface layer, which consists only platinum atoms, while the sputtered surfaces have the bulk ratio of alloying components. The measured valence band density of state spectra clearly shows the differences in electronic structures between Pt-skin and sputtered surfaces. Well-defined surfaces were hereafter transferred out from UHV and exposed to the acidic (electro)chemical environment. The electrochemical and post-electrochemical UHV surface characterizations revealed that Pt-skin surfaces are stable during and af...
892 citations
TL;DR: In this article, an equiatomic CoCrFeMnNi high-entropy alloy (HEA), produced by arc melting and drop casting, was subjected to severe plastic deformation (SPD) using high pressure torsion.
887 citations
TL;DR: The binding forces in an alloy are predominantly those between the metal atoms of both kinds on the one hand and the common electronic system on the other hand, as opposed to the binding forces between atom and atom which predominate in other chemical compounds.
Abstract: When two metals are allowed together in various proportions, a series of solid phases is formed. A characteristic phase diagram of a binary alloy system has regions of single phase, throughout which the alloy is homogeneous, alternating with regions in which two neighbouring phases coexist. The composition of a single phase can be varied continuously over a certain range. This feature of an alloy is in contrast to tire constant atomic ratio of a chemical compound, and is explained by the nature of the binding forces in an alloy which are predominantly those between the metal atoms of both kinds on the one hand and the common electronic system on the other hand, as opposed to the binding forces between atom and atom which predominate in other chemical compounds. Not only may the atomic ratio in a given phase be varied, but also an orderly space distribution of one kind of atom relative to the other, as found in topical chemical compounds, does not necessarily exist in an alloy. Although each phase is distinguished by possessing a characteristic crystalline structure which differs from that of other phases in the same alloy system, yet this structure may be merely an orderly arrangement of sites occupied by atoms. The manner in which the atoms are distributed amongst the sites of a given phase is often variable, and is, for instance, affected by the thermal treatment which the alloy has undergone.
879 citations
TL;DR: A review of the recent research results on new amorphous alloys can be found in this paper, where the main topics consist of the following five parts ; (1) the finding of new AMO alloys with extremely large glass-forming ability in a number of alloy systems, (2) the mechanism for the achievement of the large AMO ability, (3) the clarification of fundamental properties of the new amOAlloys, (4) the successful examples of producing bulk amOOD alloys by four different techniques of water quenching, metallic mold casting
Abstract: This paper aims to review our recent research results on new amorphous alloys. The main topics consist of the following five parts ; (1) the finding of new amorphous alloys with extremely large glass-forming ability in a number of alloy systems, (2) the mechanism for the achievement of the large glass-forming ability, (3) the clarification of fundamental properties of the new amorphous alloys, (4) the successful examples of producing bulk amorphous alloys by four different techniques of water quenching, metallic mold casting, arc melting and unidirectional zone melting, and (5) the high tensile strength of the bulk amorphous alloys. These new results enable the elimination of the limitation of sample shape which has prevented the development of amorphous alloys as engineering materials and are expected to give rise to the revisit age to amorphous alloys.
878 citations
TL;DR: In this paper, the catalytic activity of single-phase polycrystalline Pt-Ru bulk alloys toward the electrooxidation of methanol in sulfuric acid electrolyte at room temperature was measured for the first time on well-characterized alloy surfaces, in terms of surface composition and true surface area.
Abstract: The catalytic activity of single-phase polycrystalline Pt-Ru bulk alloys toward the electrooxidation of methanol in sulfuric acid electrolyte at room temperature was measured for the first time on well-characterized alloy surfaces, in terms of surface composition and true surface area. Sputter-cleaned and annealed alloys were prepared in ultrahigh vacuum (UHV) and the surface composition of oxygen-free surfaces was assessed via low-energy ion scattering (LEIS). Pt-Ru alloy surfaces annealed in UHV were strongly enriched in Pt, whereas the surface composition of sputter-cleaned alloys was essentially identical to their bulk composition. It was shown that the sputter-cleaned alloy with a Ru surface of [approx equal] 10 atomic % gave the highest catalytic enhancement (over pure Pt) for the steady-state electrooxidation of methanol at 25[degree]C and 0.5 V, viz., by a factor of 12 in 5.0 mM CH[sub 3]OH solution and by a factor of 30 in 0.5 M CH[sub 3]OH. It was found that the balance between the rate of methanol adsorption and the rate of the oxidative removal of dehydrogenated fragments determines the activities of Pt-Ru alloys with different Ru surface compositions. 51 refs., 9 figs., 2 tabs.
875 citations