Solute partitioning and twin nucleation: few papers

June 21, 2010

[1] Influence of interface energies on solute partitioning mechanisms in doped aluminas

S J Dillon et al

The experiments described in this paper have been designed to understand how particular dopants in alumina (Ca, Mg, Si, and Y) affect microstructural development through the energetics of their associated precipitates. Specifically, the role of the interphase boundary energy and precThe experiments described in this paper have been designed to understand how particular dopants in alumina (Ca, Mg, Si, and Y) affect microstructural development through the energetics of their associated precipitates. Specifically, the role of the interphase boundary energy and precipitation activation energy are considered to be in competition with grain boundary complexion (disorder) transitions for partitioning excess solute. The results reveal a relationship between the relative precipitation activation energy and the temperature at which grain boundary complexion transitions occur. The large differences in activation energy primarily derive from the interphase boundary energy. Precipitates that form lower interphase boundary energies tend to suppress complexion transitions, while systems that contain precipitates with high interphase boundary energies are more susceptible. Based on the findings, a new criterion for additive selection to control complexion transitions and abnormal grain growth is proposed that is based on interfacial energies between the host and precipitate.ipitation activation energy are considered to be in competition with grain boundary complexion (disorder) transitions for partitioning excess solute. The results reveal a relationship between the relative precipitation activation energy and the temperature at which grain boundary complexion transitions occur. The large differences in activation energy primarily derive from the interphase boundary energy. Precipitates that form lower interphase boundary energies tend to suppress complexion transitions, while systems that contain precipitates with high interphase boundary energies are more susceptible. Based on the findings, a new criterion for additive selection to control complexion transitions and abnormal grain growth is proposed that is based on interfacial energies between the host and precipitate.

[2] Effect of particles in promoting twin nucleation in a Mg–5 wt% Zn alloy

J D Robson et al

The number of 10View the MathML source2 twins formed in a compressed Mg–5wt% Zn alloy increased when precipitate particles were present, reaching a maximum in the peak aged condition. Particles were observed to promote twin nucleation, but inhibit twin growth. A simple model has been developed to show that in peak and over–aged condition the increase in twin number is well predicted by assuming the additional stress driving twin nucleation equates to the Orowan stress inhibiting twin growth.

[3] Nucleation of paired twins at grain boundaries in titanium

L Wang et al

An experimental study of deformation twins in a polycrystalline α-Ti bend specimen was performed. In some grain pairs, mechanical twins in adjacent grains were coincident at a grain boundary (T+T). Based on the identified T+T pairs, factors including twin system alignment, twinning Schmid factor, disorientation of the parent grains, and parent grain size were assessed. An indicative combination of geometric conditions was identified that can account for the formation of most of the observed T+T pairs.

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