Effect of heat treatment on microstructural and mechanical properties of molybdenum based PM ferrous alloys

Davoudnezhad, Ramona
In this study, the effect of different heat treatment processes on microstructural and mechanical properties of Distaloy-DH and Astaloy Mo (Fe-2Cu-1.5Mo) powders are investigated. Powder samples are sintered at 1120°C for 45 minutes in a sintering furnace under reducing atmosphere of: 10% H2 + 90% N2. After sintering, secondary heat treatments are performed on samples. Microstructural characterization of samples is done with optical and electron microscopy. Selective etching is utilized for determining the amount of bainite and martensite in samples. The Distaloy-DH samples yield approximately 1.9% less porosity than Astaloy Mo samples. In all specimens, pearlite, bainite and/or mixture of martensite and bainite phases are obtained based on the isothermal holding temperature or cooling rate from the austenite region. The study revealed that the specimens with martensitic and lower bainitic microstructure yield high TRS values with respect to either pearlitic or upper bainitic microstructures. Moreover, the lower bainitic structures yield similar or higher TRS values with respect to martensitic structures even at lower hardness values.


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The objective of this study was to investigate the effect of swaging on the microstructure and tensile properties of high density two phase alloys 90W-7Ni-3Fe and 93W-4.9Ni-2.1Fe. Samples were liquid phase sintered under hydrogen and argon at 1480 degrees C for 30 min and then 15% cold rotary swaged. Measurement of microstructural parameters in the sintered and swaged samples showed that swaging slightly increased tungsten grain size in the longitudinal direction and slightly decreased tungsten grain size i...
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The effects of lithium doping on the formation and properties of the T1-based superconductors have been studied. Lithium atoms up to around 3 mol.% have been added to the oxides of nominal composition Tl1.8Ba2Ca2.2Cu3Ox, and the usual solid-state reaction method has been applied. Lithium additions in the range 0.23-0.29 mol.% increase the fraction of the Tl-2223 phase and significantly improve the critical temperature of the samples. Higher amounts of lithium additions diminish the Tl-2223 phase, reduce the...
Effect of magnetic field and gamma irradiation on the electrical properties and structure of the Tl-based ceramic superconductors
Ozkan, H; Hasanlı, Nızamı; Kayed, T (IOP Publishing, 2000-02-01)
The voltage-current (V-I) characteristics, critical temperatures and the critical currents of Tl2Ba2CaCu2O8 (Tl-2212) and Tl2Ba2Ca2Cu3O10 (Tl-2223) ceramic superconductors were studied in magnetic fields up to 80 mT after several gamma irradiations up to 100 MR. The effect of gamma irradiation on the structure of these materials has also been studied. The normal state resistance increases by 20-30% with gamma irradiation, most of the changes taking place in low gamma doses up to 10 MR. The critical temperat...
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In this study, soft magnetic Ni-Fe permalloy compacts were consolidated through microwave and conventional sintering routes at combinations of various sintering temperatures and compaction pressures. Sintered alloys were characterized in terms of their densification, microstructural evolution as well as magnetic and machanical properties. The effect of sintering method in terms of the applied sintering parameters on the final properties of the compacts were investigated in a comparative manner. It was deter...
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Kaynak, Cevdet (SAGE Publications, 2013-11-13)
The focus of this study is to investigate the effects of oxidative functionalized carbon nanotubes (f-CNTs) and aminosilanized carbon nanotubes (s-CNTs) on the mechanical and thermal properties of polyamide 6 nanocomposites. Oxidation of nanotube surfaces was conducted with sulfuric acid/nitric acid mixture and then aminosilanization was carried out with -aminopropyltriethoxysilane. Nanocomposites were compounded by melt mixing technique and shaped by injection molding. Scanning electron microscopy images r...
Citation Formats
R. Davoudnezhad, “Effect of heat treatment on microstructural and mechanical properties of molybdenum based PM ferrous alloys,” M.S. - Master of Science, Middle East Technical University, 2016.