| 1. |
- Danno, A., et al.
(författare)
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Effect of cold severe deformation by multi directional forging on elastic modulus of multi functional Ti+25mol% (Ta,Nb,V)+(Zr,Hr,O) alloy
- 2010
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Ingår i: Materials & Design. - : Elsevier BV. - 0261-3069. ; 31:SUPPL. 1, s. S61-S65
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Tidskriftsartikel (refereegranskat)abstract
- A new and unique beta-titanium alloy (Ti. +. 25. mol% (Ta,Nb,V). +. (Zr,Hr,O) has interesting properties such as low elastic modulus, high strength and high elastic deformability as well as Invar and Elinvar properties. These properties have been successfully realized for the round wire or rods by cold working process but not enough for the sheet made by the cold rolling.To improve the mechanical properties of the alloy sheet, the effect of cold severe deformation on the elastic modulus and microstructure of the alloy sheet was experimentally investigated. The samples were processed using the multi directional forging (MDF) and cold plain rolling.The elastic modulus of the alloy sheet which was cold rolled after MDF was lower than that of cold rolled sheet without MDF. The severe cold plastic deformation by MDF was also effective for obtaining isotropic elastic modulus and very fine grain size (∌1ÎŒm) of sheet after plain rolling. The prototype sheet with low elastic modulus (60-65. GPa), high strength (1100. MPa) and high ductility (total elongation more than 10%) was successfully made in the laboratory test by combining MDF and plain rolling at room temperature. © 2009 Elsevier Ltd.
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| 2. |
- Bi, G., et al.
(författare)
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Feasibility study on the Laser Aided Additive Manufacturing of die inserts for liquid forging
- 2010
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Ingår i: Materials & Design. - : Elsevier BV. - 0261-3069. ; 31:SUPPL. 1, s. S112-S116
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the Laser Aided Additive Manufacturing of nickel-base alloy Nimonic 80A for the purpose of direct building of die inserts for liquid forging. Low porosity level of 0.01-0.04% with reasonable deposition rate was achieved. The micro-hardness showed very good homogeneity. Directionally solidified cellular micro-structure with an average size of 5Όm was observed. Very fine MC-type carbides were detected at the grain boundaries, which function as the strengthening phase of the alloy. © 2009 Elsevier Ltd.
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| 3. |
- Gorbatov, O. I., et al.
(författare)
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Effect of magnetism on short-range order formation in Fe-Si and Fe-Al alloys
- 2011
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Ingår i: International Conference on Solid-Solid Phase Transformations in Inorganic Materials, PTM 2010. - 9783037851432 ; , s. 618-623
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Konferensbidrag (refereegranskat)abstract
- Short-range order formation in dilute Fe-Si and Fe-Al alloys has been investigated by statistical Monte Carlo simulations with effective interactions deduced from first principles calculations for different magnetic structures of bcc Fe. We find that the variation of the magnetic order from ferromagnetic to paramagnetic leads to significant changes in effective cluster interactions and, as follow, in short-range order parameters of alloys. It is shown in agreement with experiment the B2 type short-range order is formed above the Curie temperature, TC, while the D03 type short-range order is preferred below TC.
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| 4. |
- Hudl, Matthias, et al.
(författare)
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Strongly enhanced magnetic moments in ferromagnetic FeMnP0.5Si0.5
- 2011
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 99:15, s. 152502-
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Tidskriftsartikel (refereegranskat)abstract
- The compound FeMnP(0.5)Si(0.5) has been studied by magnetic measurements, Mossbauer spectroscopy, and electronic structure and total energy calculations. An unexpectedly high magnetic hyperfine field for Fe atoms located at the tetrahedral Me(1) site in the Fe(2)P structure is found, The saturation moment derived from magnetic measurements corresponds to 4.4 mu(B)/f.u. at low temperatures, a value substantially higher than previously reported, but in accordance with the results from our electron structure calculations, This high saturation moment and the tunable first order ferromagnetic transition make the Fe(2-x)Mn(x)P(1-y)Si(y), system promising for magnetocaloric applications.
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| 5. |
- Menushenkov, V. P., et al.
(författare)
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Effect of heat treatment on the microstructure and magnetic properties of as-cast SmCo 5-based alloys
- 2012
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Ingår i: Magnetism and Magnetic Materials V. - : Trans Tech Publications Inc.. - 9783037854365 ; , s. 204-207
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Konferensbidrag (refereegranskat)abstract
- Local and crystalline structures of as-cast SmCo 5±x alloys subjected to various heat treatments were studied using EXAFS, X-ray diffraction, and metallographic analyses. XRD and EXAFS analyses of SmCo 5-x alloys show the evidence of the Sm-enrichment of the SmCo 5 phase. The behavior of the lattice parameters of SmCo 5 phase in Sm-rich alloys during aging between 1120°C and 700°C can be related to the phase transformation of SmCo 5 into SmCo 5-x phases.
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| 6. |
- Pande, Ashwary, et al.
(författare)
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Influence of rate of heating to aging temperature on precipitation hardening in a metastable β titanium alloy
- 2014
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Ingår i: Advanced Materials Research. - : Trans Tech Publications. - 1022-6680 .- 1662-8985. ; 1025-1026, s. 445-450
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Tidskriftsartikel (refereegranskat)abstract
- A comparison between slow heating to aging temperature and direct charging at aging temperature on the microstructure and mechanical properties obtained after the aging was established for the metastable beta (β) titanium alloy Ti-15V-3Cr-3Al-3Sn. The alloy was subjected to two single aging (SA) and two duplex aging (DA) conditions, with two heating rates to aging temperature: (i) low heating rate of 5 oC/min (ii) direct charging into a furnace heated to aging temperature. The microstructure analysis was carried out using Field Emission Scanning Electron Microscopy. Mechanical Testing was carried to evaluate Ultimate Tensile Strength (UTS), 0.2% Yield Strength (YS), % Elongation (%El.), % Reduction in area (%RA) and hardness. In the case of SA samples aged at 500 °C for 8 h and 500 °C for 10 h, heating rate of 5 °C/min to aging temperature resulted in a finer microstructure but did not help in achieving better strength-ductility combination compared to direct charging. Lower rate of heating allows enough dwell time in the temperature range 250-300 oC for pre-precipitation reaction to occur which aids in fine scale precipitation of alpha phase during aging. In the case of DA samples aged at 250 oC for 24 h followed by 500 oC for 8 h and 300 oC for 10 h followed by 500 oC for 10 h, no tangible difference between lower rate of heating and direct charging was observed in mechanical properties or microstructure. This is believed to be due to the pre-aging steps 250 oC/24 h or 300 oC/10h in the two DA treatments, which create finely distributed precursors thereby leaving no scope for the heating rate to play a role.
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| 7. |
- De Oro Calderón, Raquel, 1982, et al.
(författare)
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Effect of processing conditions on microstructural features in Mn-Si sintered steels
- 2014
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Ingår i: Materials Characterization. - : Elsevier BV. - 1044-5803. ; 95, s. 105-117
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Tidskriftsartikel (refereegranskat)abstract
- Sintering of steels containing oxidation sensitive elements is possible if such elements are alloyed with others which present lower affinity for oxygen. In this work, a master alloy powder containing Fe-Mn-Si-C, specifically designed to create a liquid phase during sintering, has been used for such purpose. The effect of processing conditions such as sintering temperature and atmosphere was studied with the aim of describing the microstructural evolution as well as the morphology and distribution of oxides in the sintered material, evaluating the potential detrimental effect of such oxides on mechanical properties. Chemical analyses, metallography and fractography studies combined with X-ray photoelectron spectroscopy analyses on the fracture surfaces were used to reveal the main mechanism of fracture and their correlation with the chemical composition of the different fracture surfaces. The results indicate that the main mechanism of failure in these steels is brittle fracture in the surrounding of the original master alloy particles due to degradation of grain boundaries by the presence of oxide inclusions. Mn-Si oxide inclusions were observed on intergranular decohesive facets. The use of reducing atmospheres and high sintering temperatures reduces the amount and size of such oxide inclusions. Besides, high heating and cooling rates reduce significantly the final oxygen content in the sintered material. A model for microstructure development and oxide evolution during different stages of sintering is proposed, considering the fact that when the master alloy melts, the liquid formed can dissolve some of the oxides as well as the surface of the surrounding iron base particles.
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| 8. |
- Eriksson, Sandra, et al.
(författare)
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Rotor design for PM generators reflecting the unstable neodymium price
- 2012
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Ingår i: Electrical Machines (ICEM), 2012 XXth International Conference. - 9781467301435 - 9781467301411 ; , s. 1419-1423
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Konferensbidrag (refereegranskat)abstract
- The price of rare earth metals such as neodymium is very unstable and has in recent years increased more than 1000%. This leaves the wind power business that uses permanent magnet generators with large insecurity. In this paper, a generator design with an interchangeable rotor is presented, which gives the option of having a rotor with different material depending on the current neodymium price. Thereby, the wind turbine has the same properties with only the generator rotor changing. The suggested alternative, a ferrite rotor, is much heavier than a neodymium rotor. The heavy ferrite rotor indicates an advantage for the vertical axis wind turbine technology with the generator placed on ground level, where the weight is not as important as in the hub. Two similar generator designs are presented, magnet material differences are discussed and the neodymium price limit for when the ferrite rotor is to be preferred is calculated.
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| 9. |
- Lohia, A., et al.
(författare)
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Deposition of Nanocomposite Coatings Employing a Hybrid APS + SPPS Technique
- 2014
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Ingår i: Journal of thermal spray technology (Print). - : Springer New York LLC. - 1059-9630 .- 1544-1016. ; 23:7, s. 1054-1064
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Tidskriftsartikel (refereegranskat)abstract
- A novel approach hybridizing the conventional atmospheric plasma spraying and the solution precursor plasma spraying techniques has been explored to develop nanocomposite coatings. The above hybrid processing route involves simultaneous feeding of an appropriate solution precursor and commercially available spray-grade powder feedstock to realize microstructures comprising nanostructured and micron-sized features, which are unique in thermal spraying. The attractive prospects offered by this hybrid technique for deposition of nanocomposite coatings are specifically highlighted in this paper through a case study. Plasma sprayed Mo-alloy coatings are known for their good tribological characteristics and widely used in many applications. Further augmentation in performance of these coatings is expected through incorporation of distributed nanostructured oxide phases in the microstructure. Successful development of such coatings using a spray-grade Mo-alloy powder and a suitable oxide-forming solution precursor has been demonstrated. Splat formation under varied processing conditions has been comprehensively investigated and related to microstructure and tribological behavior of the coatings to assess the efficacy of the above nanocomposite coatings for wear resistant applications. © 2014, ASM International.
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| 10. |
- Masood, Ansar, 1983-, et al.
(författare)
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Effect of Ni-substitution on glass forming ability, mechanical, and magnetic properties of FeBNbY bulk metallic glasses
- 2013
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 113:1, s. 013505-
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Tidskriftsartikel (refereegranskat)abstract
- We present a method to identify bulk glass forming ability by partial substitution of Fe by Ni in FeBNbY based amorphous alloy ribbons and as a consequence obtain enhanced mechanical and soft magnetic properties of bulk glassy rods of diameter as large as 4.5 mm. A detailed investigation of thermal, mechanical, and magnetic properties of (Fe0.72-x NixB0.24Nb0.04)(95.5)Y-4.5 alloys (with x similar to 0.02, 0.04, 0.06, 0.08, 0.1) was carried out. The supercooled regime (Delta T-x) and other glass forming parameters, e. g., reduced glass transition temperature (T-rg), the gamma (gamma) parameter, etc., were found to be enhanced due to the Ni substitution resulting in improvement of glass forming ability (GFA). The maximum values of such parameters (Delta T-x similar to 94 K, T-rg similar to 0.644, and gamma similar to 0.435) were obtained for the alloy with x similar to 0.06, making it possible to cast cylindrical rods with 4.5 mm diameter for this composition. Nanoindentation studies on glassy rods also point out that (Fe0.66Ni0.06B0.24Nb0.04)(95.5)Y-4.5 alloy exhibit the maximum value of hardness (H similar to 12 GPa) as well as elastic modulus (E similar to 193 GPa) among all of these samples. In addition to these, that particular sample shows the lowest room temperature coercivity (H-c similar to 210 mOe). By annealing at 823 K, H-c can be further reduced to 60 mOe due to its structural relaxation. We attribute the improved soft magnetic and mechanical properties of as-quenched (Fe0.66Ni0.06B0.24Nb0.04)(95.5)Y-4.5 alloy to higher packing density attained due to its large glass forming ability.
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