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Thursday, August 6, 2020 | History

2 edition of Ductile-brittle transition in polycrystalline chromium, molybdenum and tungsten. found in the catalog.

Ductile-brittle transition in polycrystalline chromium, molybdenum and tungsten.

Hugh Gordon Mellor

Ductile-brittle transition in polycrystalline chromium, molybdenum and tungsten.

by Hugh Gordon Mellor

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  • 5 Currently reading

Published in Bradford .
Written in English


Edition Notes

Ph. D. thesis. Typescript.

SeriesTheses
The Physical Object
Pagination1vol
ID Numbers
Open LibraryOL13723863M

3. Molybdenum alloys were expected to have a ductile-brittle transition temperature (DBTT) below room temperature in the "as-produced" condition -- and this was achieved. 4. Tungsten alloys of high strength (and high recrystalliza- tion temperature) were sought with minimum DBTT, but a DBTT below room temperature was not expected. Thermodynamics of gas phase chromium species: The chromium oxides, the chromium oxyhydroxides, and volatility calculations in waste incineration processes. Combustion and Flame , 93 (),

  Good question. And the answer is yes and no! The idea that elements have special magical properties in and of themselves is just an assumption, and quite often turns out to be just plain wrong! But magical thinking dies hard, we live with its cons. A study of molybdenum and three dilute molybdenum-rhenium alloys was undertaken to determine the effects of rhenium on the low-temperature ductility and other mechanical properties of molybdenum. Alloys containing , , and atomic percent rhenium all exhibited lower ductile-brittle transition temperatures than did the unalloyed molybdenum.

A new class of materials, which basically are single crystal alloys of molybdenum and tungsten, with abnormally high creep strength, is proposed for use. The alloys have a . Ductile-brittle transition, region, 79 temperature, , chromium-molybdenum steel, chromium-nickel-molybdenum- manganese steel, N Polycrystalline silicon film, Polymer impregnation and pyrolysis methods, Positron annihilation.


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Ductile-brittle transition in polycrystalline chromium, molybdenum and tungsten by Hugh Gordon Mellor Download PDF EPUB FB2

The fracture stress at the ductile-brittle transition temperature of polycrystalline molybdenum was found to be constant, 64± 2 kg mm −2, as the molybdenum and tungsten. book rate was raised from 5 × 10 −6 to 5 × 10 −2 sec − is suggested that only above the transition temperature is crack nucleation easier than crack propagation and that brittle molybdenum and tungsten.

book takes place at the crack nucleation by: >Ductile-brittle transition behavior occurs in the bodycentered cubic refractory metals niobium, molybdenum.

tungsten, and chromium. The available data for vanadium suggest that brittleness at low temperatures is attributable a low-stress-rate hydogen embrittlement.

However, the occurrence of ductile- brittle transition behavior is not precluded. The ductile–brittle transition temperature (DBTT) of a sintered pure chromium subjected to a kind of thermomechanical treatments was examined by a tension test.

In the present treatment, pieces cut from the sintered block were repeatedly rolled at K up to 50 and 85% in total reduction with and without the intermediate annealing at K Cited by: 4. Ductile–brittle transition of polycrystalline iron and iron–chromium alloys Article (PDF Available) in Journal of Nuclear Materials (3) September with Reads.

The values of activation energy for the brittle–ductile transition of polycrystalline Fe, Fe–3%Cr and Fe–9%Cr were found to beand eV, respectively, indicating that the.

Fracture toughness of polycrystalline Fe, Fe–3%Cr and Fe–9%Cr was measured by four-point bending of pre-cracked specimens at temperatures between 77 K and K and strain rates between × 10^−4 and × 10^−2 s−1.

For all materials, fracture. Less-Common Metals, S () DUCTILE-BRITTLE TRANSITION IN POLYCRYSTALLINE W ASHBY AND BROWN; helium bubbles in metals have been studied by BARNES AND MAZEY) The connection between low-stress failures, sintered material and bubbles (or voids) appears to be established for tungsten (mechanical properties of molybdenum.

The strain rate dependence of the brittle-to-ductile transition (BDT) temperature was investigated in notched and un-notched miniature bars made of high-purity polycrystalline tungsten and in.

Scripta METALLURGICA Vol. 3, pp.Printed in the United States Pergamon Press, Inc THE RELATION BETWEEN THE DUCTILE-BRITTLE TRANSITION TEMPERATURE AND GRAIN SIZE IN POLYCRYSTALLINE MOLYBDENUM J.

Thornley and A. Wronski School of Materials Science University of Bradford England (Received Septem ) The only comprehensive theory of the ductile-brittle transition.

The Effects of Precompression and Pressurization on the Ductile–Brittle Transition of Polycrystalline Cast Chromium, Molybdenum, and Tungsten H. Mellor & A. Wronski. The Raman spectra of polycrystalline transition metal hexacarbonyls M(CO) 6, M = Cr, Mo, W, in the 4 cm –1 region are reported.

The spectra are interpreted using a two-phonon model. In marked contrast to the spectra in the 2 cm –1 region, factor-group effects appear to be negligible, so that the spectra are much simpler than might be expected from the wealth of.

arc-melted tungsten sheet range from approximately ' to ' K and ' to ' K for wrought and recrystallized sheet, respectively (ref. High ductile-brittle transition temperatures are not peculiar to tungsten; they also characterize the other group VI metals, molybdenum and chromium (ref.

>Ductile-brittle transition behavior occurs in the bodycentered cubic refractory metals niobium, molybdenum. tungsten, and chromium.

The available data for vanadium suggest that brittleness at low. The high temperature strength of chromium can be increased three to fourfold by solution strengthening with elements such as tantalum, columbium, tungsten, molybdenum, and rhenium.

However, solution strengthening involves a significant increase in the ductile-brittle transition temperature. The strain rate dependence of the brittle-to-ductile transition (BDT) temperature was investigated in notched and un-notched miniature bars made of high-purity polycrystalline tungsten and in notched bars of less-pure sintered material.

The activation energy, E BDT, for the process controlling the BDT in pure tungsten was equal to eV both in un-notched and notched. During each revolution of the target wheel the bricks make a cycle from below the slowbending DBTT (ductile-brittle transition temperature, purity and microstructure dependent, °C for.

Correlation of Temperature and Grain Size Effects in the Ductile-Brittle Transition of Molybdenum. Passmore - - Philosophical Magazine 11 () Ductile–Brittle Transition in Micropillar Compression of GaAs at Room Temperature. Anisotropic Fracture Behaviour and Brittle-to-Ductile Transition of Polycrystalline Tungsten.

additions alloy additions alloys analysis annealing appeared arc-cast base behavior bend binary carbon chromium cold-working columbium columbium alloys compared condition conducted containing creep curves decrease deformation density ductile-brittle ductility effect elasticity elongation evaluated exhibited fabrication Figure fracture given.

The ductile-brittle transition in the fracture of α-iron: I. Petch. Philosophical Magazine 3 (34) (). Tungsten, or wolfram, is a chemical element with the symbol W and atomic number The name tungsten comes from the former Swedish name for the tungstate mineral scheelite, tungsten which means "heavy stone".

Tungsten is a rare metal found naturally on Earth almost exclusively combined with other elements in chemical compounds rather than alone. It was.

The dependence of the flow stress of high‐purity α‐iron monocrystals on temperature and strain rate, measured by successive tensile deformations at temperatures between and K and correlated stress‐relaxation tests, is analysed by means of Seeger's theory of thermally activated kink‐pair formation in screw dislocations.MOST metals other than those having a face-centred cubic structure show a more or less rapid transition from ductile to brittle behaviour as the temperature is lowered.

Well above the transition.used to manufacture molybdenum-alloy steel. During melting, the gangue ends up in the slag. However, tech oxide must be purified chemically to use it in the manufacture of molybdenum metal. Figure 1 is a flow chart of molybdenum metal manufacturing, starting with tech oxide.

The oxide is first dissolved in ammonium or sodium hydroxide, and this.