Development of Aluminium Alloys with Ultimate Recrystallisation Resistance

2007 ◽  
Vol 539-543 ◽  
pp. 167-172 ◽  
Author(s):  
Håkon Hallem ◽  
Børge Forbord ◽  
Knut Marthinsen
Keyword(s):  
Cold Rolling ◽  
High Temperatures ◽  
Aluminium Alloys ◽  
High Price ◽  
Special Focus ◽  
Number Density ◽  
Alloying Element ◽  
Precipitation Behaviour ◽  
Very High ◽  
Zr Alloy

In the present work the precipitation behaviour and recrystallisation resistance of Alalloys containing Hf, Sc and Zr in different concentrations and combinations have been investigated. Special focus has been put on the Hf-containing alloys, as one of the objectives of this work was to find out if Hf can be used as a replacement for Sc. Additions of Sc, either alone or in combination with Zr, leads to the formation of coherent and homogeneously distributed dispersoids, which very efficiently inhibit recrystallisation. Despite these attractive properties, the high price of Sc has limited its use as an alloying element in aluminium. The present investigation has revealed that Hf cannot fully replace Sc, as only heterogeneous dispersoid distributions are obtained in the absence of Sc, i.e. in regions where the number density is low the alloys would still be prone to recrystallisation. However, as an extra addition to the already remarkably stable Sc+Zr-containing alloys, Hf can lead to further improvements and consequently open for the use of aluminium alloys at very high temperatures. Al3(Sc,Zr,Hf)-dispersoids were present at the largest f/r-ratios and also displayed lower coarsening rates than Al3(Sc,Zr)-dispersoids. Very promising results were obtained for an Al-Hf-Sc-Zr alloy, which maintained mainly an unrecrystallised structure after extrusion and large degrees of cold rolling.

Recrystallisation Resistance of Extruded and Cold Rolled Aluminium Alloys with Additions of Hf, Sc and Zr

2006 ◽  
Vol 519-521 ◽  
pp. 525-530 ◽  
Author(s):  
Håkon Hallem ◽  
W.J. Rittel ◽  
Børge Forbord ◽  
Knut Marthinsen
Keyword(s):  
Cold Rolling ◽  
Structural Stability ◽  
High Temperatures ◽  
High Resistance ◽  
Aluminium Alloys ◽  
Cold Rolled

A high recrystallisation resistance is required in aluminium alloys intended for processing or use at temperatures between 450°C-600°C. Additions of Hf, Sc and Zr significantly improve the resistance to recrystallisation through the formation of Al3X-dispersoids (X=Hf,Sc,Zr), and in this work different concentrations and combinations of these elements were added to five aluminium alloys. The alloys were extruded, subjected to various degrees of cold rolling (0%-80%) and finally annealed at high temperatures in order to study the structural stability. All variants displayed a high resistance towards recrystallisation, but the best results were obtained in the alloy containing only Sc and Zr. In this alloy no signs of recrystallisation were observed even after 1 hour annealing of extruded and 80% cold rolled profiles at 600°C.

The Effect of Heating Rate on the Density and Spatial Distribution of Dispersoids during Homogenisation of 6xxx Aluminium Alloys

2016 ◽  
Vol 877 ◽  
pp. 322-327 ◽  
Author(s):  
Magnus S. Remøe ◽  
Knut Marthinsen ◽  
Ida Westermann ◽  
Ketill Pedersen ◽  
Jostein Røyset ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Heating Rate ◽  
Aluminium Alloys ◽  
Rapid Heating ◽  
Number Density ◽  
Heating Rates ◽  
Precipitation Behaviour ◽  
Quantitative Analyses ◽  
Mn Content

Two 6xxx alloys with different Mn-content have been homogenised in a furnace at 575 oC for 2 hours and 15 minutes. Three different heating rates to the homogenisation holding temperature were chosen, as this was expected to affect the precipitation behaviour of the dispersoids. The study focused on developing a reliable procedure for the characterization of the density and spatial distribution of dispersoids in aluminium alloys; both in terms of sample preparation, microscopic techniques and quantitative analyses of results. Scanning electron microscopy (SEM) has been used to evaluate the dispersoid characteristics for the different alloys and heating rates. The results indicate an increase in dispersoid number density and a more uniform distribution of dispersoids for the lowest heating rate, as compared to the more rapid heating rates, for the alloy with 0.05 wt% Mn. For the alloy with 0.15 wt% Mn the number density increased with the heating rate. This is suggested to be due to particle coarsening as an effect of the low heating rate where the samples spend longer time in the furnace.

Beyond Ni-based superalloys: Development of CoRe-based alloys for gas turbine applications at very high temperatures

2011 ◽  
Vol 102 (9) ◽  
pp. 1125-1132 ◽  
Author(s):  
Debashis Mukherji ◽  
Joachim Rösler ◽  
Pavel Strunz ◽  
Ralph Gilles ◽  
Gerhard Schumacher ◽  
...  
Keyword(s):  
Gas Turbine ◽  
High Temperatures ◽  
Very High

Rolling and Recrystallization Textures in High Purity Al Cold Rolled to Very High Rolling Reductions

2005 ◽  
Vol 495-497 ◽  
pp. 603-608 ◽  
Author(s):  
Atsushi Todayama ◽  
Hirosuke Inagaki
Keyword(s):  
Cold Rolling ◽  
High Purity ◽  
Work Hardening ◽  
Dynamic Recovery ◽  
The Other ◽  
Rolling Reduction ◽  
Theoretical Investigations ◽  
Theoretical Predictions ◽  
Cold Rolled ◽  
Very High

On the basis of Taylor-Bishop-Hill’s theory, many previous theoretical investigations have predicted that, at high rolling reductions, most of orientations should rotate along theβfiber from {110}<112> to {123}<634> and finally into the {112}<111> stable end orientations. Although some exceptions exist, experimental observations have shown, on the other hand, that the maximum on the β fiber is located still at about {123}<634> even after 97 % cold rolling. In the present paper, high purity Al containing 50 ppm Cu was cold rolled up to 99.4 % reduction in thickness and examined whether {112}<111> stable end orientation could be achieved experimentally. It was found that, with increasing rolling reduction above 98 %, {110}<112> decreased, while orientations in the range between {123}<634> and {112}<111> increased, suggesting that crystal rotation along the βfiber from {110}<112> toward {123}<634> and {112}<111> in fact took place. At higher rolling reductions, however, further rotation of this peak toward {112}<111> was extremely sluggish, and even at the highest rolling reduction, it could not arrive at {112}<111>. Such discrepancies between theoretical predictions and experimental observations should be ascribed to the development of dislocation substructures, which were formed by concurrent work hardening and dynamic recovery. Since such development of dislocation substructures are not taken into account in Taylor-Bishop-Hill’s theory, it seems that they can not correctly predict the development of rolling textures at very high rolling reductions, i. e. stable end orientations. On annealing specimens rolled above 98 % reduction in thickness, cube textures were very weak, suggesting that cube bands were almost completely rotated into other orientations during cold rolling. {325}<496>, which lay at an intermediate position between {123}<634> and {112}<111> along theβfiber, developed strongly in the recrystallization textures.

Interferometric testing at very high temperatures by TV holography (ESPI)

1988 ◽  
Vol 28 (3) ◽  
pp. 315-321 ◽  
Author(s):  
J. T. Malmo ◽  
O. J. Jøkberg ◽  
G. A. Slettemoen
Keyword(s):  
High Temperatures ◽  
Very High

Influence of cold rolling on the precipitation in an Al–Mn–Zr alloy

2015 ◽  
Vol 85 ◽  
pp. 361-366 ◽  
Author(s):  
M. Karlík ◽  
M. Vronka ◽  
P. Haušild ◽  
M. Hájek
Keyword(s):  
Cold Rolling ◽  
Zr Alloy

scholarly journals Gaseous combustion at high pressures. —Part X. The co-volume corrections, maximum temperatures and dissociation of steam and carbon dioxide in explosions

1928 ◽  
Vol 119 (782) ◽  
pp. 464-480
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Internal Energy ◽  
High Temperatures ◽  
High Pressures ◽  
Internal Combustion ◽  
Systematic Survey ◽  
Explosion Method ◽  
Maximum Temperatures ◽  
Very High

During the researches upon high-pressure explosions of carbonic oxide-air, hydrogen-air, etc., mixtures, which have been described in the previous papers of this series, a mass of data has been accumulated relating to the influence of density and temperature upon the internal energy of gases and the dissociation of steam and carbon dioxide. Some time ago, at Prof. Bone’s request, the author undertook a systematic survey of the data in question, and the present paper summarises some of the principal results thereof, which it is hoped will throw light upon problems interesting alike to chemists, physicists and internal-combustion engineers. The explosion method affords the only means known at present of determining the internal energies of gases at very high temperatures, and it has been used for this purpose for upwards of 50 years. Although by no means without difficulties, arising from uncertainties of some of the assumptions upon which it is based, yet, for want of a better, its results have been generally accepted as being at least provisionally valuable. Amongst the more recent investigations which have attracted attention in this connection should be mentioned those of Pier, Bjerrum, Siegel and Fenning, all of whom worked at low or medium pressures.

MAS-NMR at very high temperatures

2004 ◽  
Vol 26 (2) ◽  
pp. 84-86 ◽  
Author(s):  
Leo van Wüllen ◽  
Georg Schwering ◽  
Ernst Naumann ◽  
Martin Jansen
Keyword(s):  
High Temperatures ◽  
Mas Nmr ◽  
Very High
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