Xuyang Wang

Tailoring the Microstructure of a β -Solidifying TiAl Alloy by Controlled Post-solidification Isothermal Holding and Cooling

In this study, the microstructure of a β-solidifying TiAl alloy was modified by means of temperature-controlled cooling. The microstructural evolution of the Ti-44.5Al-4Nb-2Cr-0.1B alloy in different cooling processes was investigated. The results showed firstly that both the solidification-segregation (S-segregation) and β-segregation were reduced considerably by raising the temperature or extending the time in the single β-phase region. Then samples were cooled through the βxa0+xa0α phase region at the cooling rates of 2, 50, and 650xa0K/min. The B2-phase and some large γ-phases exist in lamellar microstructure, which might be more evident at a higher cooling rate. Further, the Burgers relationships of {0001}α2//{110}β(B2) and {11

Evolution of B2(ω) region in high-Nb containing TiAl alloy in intermediate temperature range

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Pseudobinary eutectics in Cu-Ag-Ge alloy droplets under containerless condition

2¯0}α2//{111}β(B2) were identified in the fast cooling microstructure, and the non-Burgers equiaxed α-grains grew easily at a slow cooling rate.

The Effect of Pressure Stress on the Evolution of B2(ω) Phase in High Nb Containing TiAl Alloy

AbstractIn this study, the location, morphology and composition of the ωo phase, which transformed from B2 phase in Ti–45Al–8.5Nb-(W, B, Y) (at.%) alloy, were investigated by short-time heat treatments in an intermediate temperature range. The results showed that the characteristics of B2xa0→xa0ωo phase transformation differ with the reduction in temperature. Below the ωo solves, the B2xa0→xa0ωo phase transformation will take place within B2 area. There are existing two stages in the phase transformations during cooling from 850 to 700xa0°C. When the temperature is high (850xa0°C), granular ωo populated along the dislocations existing in B2 phase and B2 grain boundaries, due to higher energy and the enrichment of Nb element at the B2/γ boundaries. It is worth noting that only two ωo variants nucleate at 850xa0°C. With the decrease in temperature, the nucleation sites of ωo phase would be migrated from the B2 boundaries to the inner area. At the temperature of 700xa0°C, four ωo variants with different orientations nucleate homogenously within B2 grain. The ordered ωo formation process of Ti–45Al–8.5Nb-(W, B, Y) alloy during cooling was postulated in this study.n