Effect of aluminum content on the decomposition kinetics of supersaturated solid solution in Mg-Al-alloys

The microstructure and thermal diffusivity of as-cast AM60, AE63, AJ63 and AXJ620 alloys were investigated over the temperature range 20–300°C. The microstructure of as-cast AM60 magnesium alloy consists of dendrites of α-Mg solid solution and divorced eutectic containing “islands” of α-Mg and Mg17Al12 phase. In regions adjacent with divorced eutectic, the supersaturation aluminum solute in the α-Mg matrix is observed. The addition of rare earth, calcium and strontium caused the decrease of the volume fraction of Mg17Al12 compound and aluminum content in α-Mg solid solution. Moreover, the intermetallic compounds such as: Al11RE3, Al4Sr, Al3Mg13Sr, Al2Ca are observed in the interdendritic regions. The thermal diffusivity of AM60 magnesium alloy increases with increasing temperature up to 150°C, above this temperature the increase is less marked. The change in the slope of the temperature variation of the thermal diffusivity is caused by a precipitation of Mg17Al12 phase in the supersaturation of α-Mg areas neighboring the divorced eutectic α-Mg+Mg17Al12. The addition of rare earth, calcium and strontium caused the increase of the thermal diffusivity and thermal conductivity due to the decreasing of aluminum content in α-Mg matrix.

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Spinodal Decomposition in Fe-Cr Alloys

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.172-174.443 ◽

2011 ◽

Vol 172-174 ◽

pp. 443-448

Author(s):

Orlando Soriano Vargas ◽

Erika O. Avila Davila ◽

Victor M. Lopez-Hirata ◽

Maribel L. Saucedo-Muñoz

Keyword(s):

Solid Solution ◽

Mechanical Behavior ◽

Spinodal Decomposition ◽

Growth Kinetics ◽

Supersaturated Solid Solution ◽

Rich Phase ◽

Hardening Behavior ◽

Plate Shape ◽

Kinetics Of ◽

Preferential Alignment

The hardening behavior of precipitation was studied during aging of Fe-Cr alloys. This mechanical behavior is associated with the nanometric modulation structure of the coherent decomposed Fe-rich and Cr-rich phases formed by the spinodal decomposition of the supersaturated solid solution. The growth kinetics of spinodal decomposition was very slow and it increased during coarsening stage. The morphology of decomposed phases consisted of an interconnected irregular shape with no preferential alignment for short aging times and a further aging caused the change to a plate shape of the decomposed Cr-rich phase aligned in the <110> directions of the Fe-rich matrix. The rapid increase in hardness and embrittlement seem to be associated with the coherency and nanometer size of the spinodally-decomposed phases in the aged alloys.

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Decomposition of the supersaturated solid solution in Ni-Cr-Fe-Nb-Al alloys and their heat treatment

Metal Science and Heat Treatment ◽

10.1007/bf00775589 ◽

1991 ◽

Vol 33 (5) ◽

pp. 376-379 ◽

Cited By ~ 1

Author(s):

G. I. Nosova ◽

V. D. Plakhtii ◽

N. A. Polyakova

Keyword(s):

Heat Treatment ◽

Solid Solution ◽

Supersaturated Solid Solution ◽

Al Alloys

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On the Precipitation Behavior at 250 and 300 °C of WE54 Supersaturated Solid Solution

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.629.85 ◽

2012 ◽

Vol 629 ◽

pp. 85-89 ◽

Cited By ~ 1

Author(s):

S. Tighiouaret ◽

H. Azzeddine ◽

A. Sam ◽

A. Sari ◽

B. Alili ◽

...

Keyword(s):

Solid Solution ◽

Supersaturated Solid Solution ◽

Precipitation Sequence ◽

Micro Hardness ◽

X Ray Diffraction ◽

Precipitation Behavior ◽

X Ray ◽

The Mean ◽

Kinetics Of

The current study seeks to further understand the precipitation sequence in a WE54 Mg alloy using in situ X-ray diffraction, micro-hardness and electrical resistivity during ageing at 250 and 300 °C. We show that the mean hardening effect is due to the precipitation of β' and β1metastable phases. The analysis of the kinetics of the precipitation shows that both phases nucleate at grain boundaries and within grains in the form of plates.

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