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Rapid solidification behaviour of Fe and Al based alloys
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. (Casting of Metals)
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Rapid solidification experiment on Fe-Cr-Mo-Mn-Si-C alloy was performed to investigate metastable phases formed during the solidification. A wide range of cooling rate was used to analyse the sample from melt spinning technique (~107 K/s) to water quenching method (~102 K/s). A single phase featureless structure was obtaind initially in the melt spinning experiment for 77Fe-8Cr-6Mn-5Si-4C alloy. Reduction of C and addition of Mo led to form a complete featureless structure for 2.85 mm rod for 72.8Fe-8Cr-5Mo-6Mn-5Si-3.2C. Subsequent investigation of influence of Mo, Cr and Mn on the single phase featureless structure concludes that 7.5 mm thick complete featureless phase could be formed at 63.8Fe-15Cr-7Mo-6Mn-5Si-3.2C alloy composition. In a separate attempt, powder samples of 40 μm dia. size complete featureless powders were produced for three slightly different compostions for the same alloy system.

Characterisation of the featureless phases reveals that it could be a single phase metastable structure of ε phase or austenitic solid solution with high amount of alloying element dissolved in it. Subsequent heat treatment of this featureless phase of the rod and the powder at different temperatures formed bainitic ferrite with fine carbides dispersed in the austenitic matrix. Hardness values measured on featureless phase found to have influenced by the alloying element specially Mo, Cr and Mn.

In an attempet to improve clean melting condition to extend the featureless phase and to form amorphous, an elliptic short arc lamp vaccum furnace was designed with 10 kW lamp power. Around 30 g of iron based alloy system was melted and cast as a 7 mm rod sample in a copper mould. Design details of new mirror and the lamp furnace are presented.

In a separate study, influence of the melt temperature on Al-Y and Al-Si alloys were investigated by levitaion casting in a silver mould at around 2000 K/s cooling rate. Plate like structure of Al8Y3 primary phase was observed at low melt temperature with small percentage of peritectic transformation of Al8Y3 and liquid melt into Al9Y2. A pre-dentritic star like crystal of Al3Y was observed in a fine eutectic matrix at very high melt temperature. Amount and number of primary Si crystals formed in a unit area during the solidification increases as the melt temperature increases.

Place, publisher, year, edition, pages
Stockholm: KTH , 2009. , 46 p.
Series
Trita-MG, ISSN 1104-7127 ; 2009:04
Keyword [en]
Rapid solidification, Melt spinning, Metastable phases, Fe based alloys.
National Category
Metallurgy and Metallic Materials
Identifiers
URN: urn:nbn:se:kth:diva-11325ISBN: 978-91-7415-464-1 (print)OAI: oai:DiVA.org:kth-11325DiVA: diva2:273923
Public defence
2009-11-13, F3, Lindstedtsvägen 26, KTH, 13:00 (English)
Opponent
Supervisors
Note
QC 20100805Available from: 2009-10-26 Created: 2009-10-26 Last updated: 2010-08-05Bibliographically approved
List of papers
1. Rapid solidification behavior of Fe-Cr-Mn-Mo-Si-C alloys
Open this publication in new window or tab >>Rapid solidification behavior of Fe-Cr-Mn-Mo-Si-C alloys
2007 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 38, no 6, 917-926 p.Article in journal (Refereed) Published
Abstract [en]

The rapid solidification behavior of alloys in the Fe-Cr-Mn-Mo-Si-C system was investigated for different compositions and cooling rates. The C content was varied and alloying additions of Mo and B were studied with respect to their effect on the microstructure. The alloys were cast as either melt-spun ribbons or as 1-mm-thick plates after levitation or as rods 2 to 4 mm in diameter by injection into copper molds. A homogeneous single-phase structure was obtained for the alloy of composition 72.8Fe-8Cr-6Mn-5Si-5Mo-3.2C (wt pct), for a sample diameter of 2.85 mm, at a cooling rate of approximate to 1100 K/s. The single-phase structure was identified as a metastable solid solution, exhibiting the characteristics of the e phase. Upon reheating, decomposition of the single-phase structure into fine bainite plates and secondary carbides was observed between 600 degrees C and 700 degrees C. The annealed structure obtained showed high hardness values (> 850 HV).

Keyword
bulk metallic glasses; amorphous-alloys; epsilon-phase; steel
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-7309 (URN)10.1007/s11663-007-9108-4 (DOI)000251925700009 ()2-s2.0-37449031278 (Scopus ID)
Note
QC 20100805Available from: 2007-06-07 Created: 2007-06-07 Last updated: 2017-12-14Bibliographically approved
2. Influence of Mo in the structure of rapidly solidified Fe-Mo-Cr-Mn-Si-C alloy
Open this publication in new window or tab >>Influence of Mo in the structure of rapidly solidified Fe-Mo-Cr-Mn-Si-C alloy
2009 (English)In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 22, no 1-4, 264-267 p.Article in journal (Refereed) Published
Abstract [en]

An Fe-Mo-Cr-Mn-Si-C alloy was prepared in an induction furnace and was cast into cylindrical rod in a copper mould in castmatic equipment (low pressure casting). A single phase non-equilibrium featureless (no visible microstructures after deep etching) phase was observed over a certain range of thickness of the rod. In this present work, the extent of the featureless phase was studied with different concentrations of Mo (5-25 wt-%) for 5.5 mm diameter of cylindrical rod at a cooling rate of 1100 K s(-1). Light optical microscopy, scanning electron Microscopy and Vickers hardness tests were used to analyse the samples. The amount of the featureless area varies as the Mo content changes and the maximum featureless area was obtained for 7 wt-% of Mo. This single phase featureless structure exhibits very high hardness (>1350 HV) which can be used in many interesting applications with or without suitable heat treatments.

Keyword
Rapid solidification, Fe-Mo-Cr-Mn-Si-C alloy, Effects of Mo, Featureless
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-11338 (URN)10.1179/136404609X367902 (DOI)000268395500065 ()2-s2.0-70350516337 (Scopus ID)
Note
QC 20100805 2nd International Conference on Advances in Solidification Process, Graz, AUSTRIA, JUN 17-20, 2008Available from: 2009-10-27 Created: 2009-10-27 Last updated: 2017-12-12Bibliographically approved
3. Influence of Cr and Mn on rapidly solidified Fe-Cr-Mo-Mn-Si-C alloy system.
Open this publication in new window or tab >>Influence of Cr and Mn on rapidly solidified Fe-Cr-Mo-Mn-Si-C alloy system.
2009 (English)Report (Other academic)
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-14422 (URN)KTH/MSE 09/59--SE+CER/ART (ISRN)
Note
QC 20100805Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2010-08-05Bibliographically approved
4. Investigation of microstructures of a rapidly cooled Fe-Cr-Mn-Si-Mo-C alloy after different heat treatments.
Open this publication in new window or tab >>Investigation of microstructures of a rapidly cooled Fe-Cr-Mn-Si-Mo-C alloy after different heat treatments.
2007 (English)In: Proceedings of the 5th Decennial International Conference on Solidification processing, UK, July 2007, 2007, 723-726 p.Conference paper, Published paper (Refereed)
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-14425 (URN)
Note
QC 20100805Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2010-08-05Bibliographically approved
5. Influence of melt temperature on Rapid solidification of Al-Y and Al-Si alloy system
Open this publication in new window or tab >>Influence of melt temperature on Rapid solidification of Al-Y and Al-Si alloy system
2009 (English)In: Transactions of the Indian Institute of Metals, ISSN 0019-493X, Vol. 62, no 4-5, 515-519 p.Article in journal (Refereed) Published
Abstract [en]

Solidification behavior of Al-Y and Al-Si were investigated for different melt temperatures. Levitation casting technique was used to achieve a cooling rate of around similar to 2000K/s during the experiment. Light optical microscopy (LOM) and Scanning electron microscopy (SEM) were used to analyze the samples. An energy dispersive system (EDS) analysis of SEM was performed on the samples to identify the phases. Plate like structure of Al8Y3 primary phase was observed at low melt temperature with small percentage of peritectic transformation of Al8Y3 and liquid melt into Al9Y2. A pre-dentritic star like crystal of Al3Y was observed in a fine eutectic matrix at very high melt temperature. Amount and number of primary Si crystals formed in a unit area during the solidification increases as the melt temperature increases. It is believed the melt temperature affects the solidification pattern by changing chemical short range order.

Keyword
rapid solidification, Al-Y alloy, Al-Si alloy, melt temperature, Al8Y3, Al3Y
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-14424 (URN)000276133700051 ()
Note
QC 20100805Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
6. Designing of Ellipsoidal high energy Short Arc Lamp Furnace.
Open this publication in new window or tab >>Designing of Ellipsoidal high energy Short Arc Lamp Furnace.
2009 (English)Report (Other academic)
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-14423 (URN)KTH/MSE--09/61--SE+CER/ART (ISRN)
Note
QC 20100805Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2010-08-05Bibliographically approved

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