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  • Metallography and Microstructures of Zirconium, Hafnium

    Zirconium, hafnium, and their alloys are reactive metals used in a variety of nuclear and chemical processing applications. This article describes various specimen preparation procedures for these materials, including sectioning, mounting, grinding, polishing, and etching.

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  • Zirconium and Hafnium Metals Handbook Desk Edition, 2nd

    This article discusses the general characteristics, primary and secondary fabrication methods, product forms, and corrosion resistance of zirconium and hafnium. It describes the physical metallurgy of zirconium and its alloys, providing details on allotropic transformation and anisotropy that profoundly influences the engineering properties of

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  • Zirconium and Hafnium Statistics and Information

    The principal economic source of zirconium is the zirconium silicate mineral, zircon (ZrSiO4). Zircon is the primary source of all hafnium. Zirconium and hafnium are contained in zircon at a ratio of about 50 to 1. Zircon is a coproduct or byproduct of the mining and processing of heavy-mineral sands for the titanium minerals, ilmenite and rutile, or tin minerals.

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  • Sintering Mechanisms of Zirconium and Hafnium Carbides

    Jun 26, 2009· The microstructure of two pressureless‐sintered ultra‐high‐temperature ceramics, namely ZrC+20 vol% MoSi 2 and HfC+20 vol% MoSi 2, was characterized by scanning and transmission electron microscopy.With regard to the ZrC–MoSi 2 system, Zr x Si y compounds and SiC were detected. In the HfC–MoSi 2 system, a mixed phase was detected at the triple points and identified as (Mo,Hf) 5

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  • Refractory Diborides of Zirconium and Hafnium

    May 10, 2007· This paper reviews the crystal chemistry, synthesis, densification, microstructure, mechanical properties, and oxidation behavior of zirconium diboride (ZrB 2) and hafnium diboride (HfB 2) ceramics.The refractory diborides exhibit partial or complete solid solution with other transition metal diborides, which allows compositional tailoring of properties such as thermal expansion coefficient

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  • Microstructure of Zirconium Alloys and Effects on Performance

    Microstructure, as the word suggests, is the small scale structure of a zirconium alloy that usually cannot be seen by the eye alone. Although invisible at a macro-scale, microstructure has a dominating effect on most of the performance-related macro-properties of a reactor component:

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  • Sintering Mechanisms of Zirconium and Hafnium Carbides

    Jun 26, 2009· The microstructure of two pressureless‐sintered ultra‐high‐temperature ceramics, namely ZrC+20 vol% MoSi 2 and HfC+20 vol% MoSi 2, was characterized by scanning and transmission electron microscopy.With regard to the ZrC–MoSi 2 system, Zr x Si y compounds and SiC were detected. In the HfC–MoSi 2 system, a mixed phase was detected at the triple points and identified as (Mo,Hf) 5

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  • Refractory Diborides of Zirconium and Hafnium

    May 10, 2007· This paper reviews the crystal chemistry, synthesis, densification, microstructure, mechanical properties, and oxidation behavior of zirconium diboride (ZrB 2) and hafnium diboride (HfB 2) ceramics.The refractory diborides exhibit partial or complete solid solution with other transition metal diborides, which allows compositional tailoring of properties such as thermal expansion coefficient

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  • Zirconium and Hafnium Statistics and Information

    The principal economic source of zirconium is the zirconium silicate mineral, zircon (ZrSiO4). Zircon is the primary source of all hafnium. Zirconium and hafnium are contained in zircon at a ratio of about 50 to 1. Zircon is a coproduct or byproduct of the mining and processing of heavy-mineral sands for the titanium minerals, ilmenite and rutile, or tin minerals.

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  • Zirconium Alloys an overview ScienceDirect Topics

    Zirconium and hafnium (used as a neutron absorber) are unique among materials used in LWRs in that they have the hexagonal close packed (HCP) crystallographic structure. The microstructure was studied by transmission electron microscopy (TEM). The specimens for TEM were prepared by the usual procedure. The electron microscope was a Tesla BS

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  • INTRODUCTION OF SCANDIUM, ZIRCONIUM AND HAFNIUM

    Keywords: Aluminum, scandium, zirconium, hafnium, alloy, intermetallic compounds (IMC), slag, inclu-sions, microstructure. Received: 16 June 2014 Revised: 30 June 2014 1. Introduction Small additions of scandium, as well as zirconium and hafnium to aluminum and aluminum-based alloys abruptly increase their strength characteristics. For example

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  • Separation of hafnium and zirconium by liquid-liquid

    Hafnium is associated with zirconium in all natural occurring ores to approximately 2 per cent by weight. Hafnium, having a high neutron cross-section, must be removed from the zirconium prior to use in nuclear reactors, Hudswell (8) has reviewed the separation of hafnium and zirconium prior to 19U9. Hafnium-free zirconium has been prepared by

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  • Sintering Behavior, Microstructure, and Mechanical

    Nearly fully dense carbides of zirconium, hafnium, and tantalum were obtained by pressureless sintering at 1950°C with the addition of 5–20 vol% of MoSi 2 . Increasing the amount of sintering aid, the final density increased too, thanks to the formation of small amounts of liquid phase constituted by M-Mo-Si-O-C, where M is either Zr, Hf, or Ta.

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  • 17 ntrs.nasa.gov

    of PG containing zirconium or hafnium. About a four-fold increase in flexure strength had been achieved with a zirconium alloy, and the oxidation resistance was also much greater, in arc-plasma tests, than that of unalloyed PG due to the formation of the refractory ZrO 2 in an oxidizing environment. Similar behavior was expected of hafnium alloys.

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  • Influence of hafnium presence on the properties and

    Hafnium is used for nuclear reactor control rods because of its ability to absorb neutrons and its . good mechanical and corrosion resistance qualities. Its neutron-capture cross-section is about 600 . times that of zirconium. Hafnium resists to corrosion due to the

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  • The Influence of Grain Boundary Elements on Properties and

    general, the heat treated pancake microstructures had uniform, supersolvus grain size, relatively consistent across all compositions. Boron had a noticeable effect on grain boundary structure, with increased boron tending to promote grain boundary filming and triple point voiding. Hafnium led to grain boundary eutectic and HfC formation (Figure

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  • 1 Thomas E. Garner, Zirconium and Hafnium Minerals, from

    16 Timothy Adams, "Zirconium and Hafnium," from Mineral Facts and Problems, U.S. Bureau of Mines, 1985, pp. 941-956. A less complicated method may be found to separate hafnium from zirconium and to refine the hafnium. A new process is being developed where zirconium and hafnium are separat ed by fractional distillation of the zirconium

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  • Sintering Mechanisms of Zirconium and Hafnium Carbides

    The microstructure of two pressureless‐sintered ultra‐high‐temperature ceramics, namely ZrC+20 vol% MoSi 2 and HfC+20 vol% MoSi 2, was characterized by scanning and transmission electron microscopy.With regard to the ZrC–MoSi 2 system, Zr x Si y compounds and SiC were detected. In the HfC–MoSi 2 system, a mixed phase was detected at the triple points and identified as (Mo,Hf) 5 Si 3.

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  • Zirconium chemical element Britannica

    Zirconium (Zr), chemical element, metal of Group 4 (IVb) of the periodic table, used as a structural material for nuclear reactors. atomic number 40 atomic weight 91.22 melting point 1,852 °C (3,366 °F) boiling point 3,578 °C (6,472 °F) specific gravity 6.49 at 20 °C (68 °F) oxidation state +4

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  • Zirconium and hafnium: Old minerals finding new prominence

    Jan 30, 2019· Hafnium is chemically similar to zirconium and separating the two elements is difficult. Because of this, most commercial hafnium is a by-product of zirconium refining. Zircon is the primary source of all hafnium, containing it at a ratio of about 50 to 1.

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