Interreactions of TiAl<SUB>3</SUB> Thin Film on Bulk &gamma;-TiAl and on Bulk &alpha;<SUB>2</SUB>-Ti<SUB>3</SUB>Al Alloys at 700&mdash;1000&deg;C

Abstract

Interreactions of diffusion couples of TiAl 3 film on bulk -TiAl and TiAl 3 film on bulk 2 -Ti 3 Al are investigated at high temperature. Experimental results show that TiAl 2 layer and TiAl 2 /-TiAl mixed layers are observed at the interfaces of TiAl 3 film/bulk -TiAl and TiAl 3 film/bulk 2 -Ti 3 Al diffusion couples, respectively, at 700$1000C. In addition, the growth rates of TiAl 2 and -TiAl product layers comply well with a parabolic law. The growth activation energy, Q k , of the TiAl 2 phase in the TiAl 3 film/bulk -TiAl system is calculated as 158.9 kJ/ mol, and Q k values of -TiAl and TiAl 2 phases in TiAl 3 film/bulk 2 -Ti 3 Al system are 163.4 kJ/mol and 147.9 kJ/mol, respectively. These Q k values are similar in magnitude with those of TiAl 3 phase formation in Ti-Al thin film diffusion systems. In this study, TiAl 2 formation is suggested to have been nucleated at the interface during the heating prior to reaching the set temperature.

A review on differential scanning calorimetry as a tool for thermal assessment of nanostructured coatings

“…melting of Al) take place in the temperature range 20-1000°C, proving it is the single intermetallic compound formed in the EB-PVD process. The activation energy of the TiAl intermetallic compound formation was estimated around 143.6 kJ mol À1 , close to 158.9 kJ mol À1 previously reported in [11].…”

Interdiffusion Behavior of Aluminide Coated Two-Phase α2-Ti3Al/γ-TiAl Alloys at High Temperatures

“…Other studies on interdiffusion layer growth on TiAl systems were conducted in diffusion couples and less complex systems of binary TiAl [9,10,11]. The values of k for TiAl 2 growth in a binary TiAl system at 700, 800 and 900 °C obtained by Chu and Wu [10] , respectively. Normally, they fit for n = 0.5, which represents purely diffusion-controlled growth.…”

“…Nevertheless, during operation of an engine abnormal combustion or a malfunction could occur, leading to overheating and altering the performance of the coated materials. Several researchers [9][10][11] have studied interdiffusion in Ti-Al systems. However, they worked with relatively simple systems of binary Ti-Al.…”