224 Prakt. Met. Sonderband 38 (2006) 
2. EXPERIMENTAL as 
sin 
The chemical composition in wt% of Ti-10-2-3 is: 9.24V, 3.25Al, 1.86Fe, 0.023C, 0.011N, WE 
0.0008H, less than 0.005Y and the rest of Ti. The Tg determined by the supplier for this CO! 
alloy is 808°C [6]. sh 
Cylindrical specimens of 15 mm length and 10 mm diameter were machined with the DE 
cylinder compression axis perpendicular to the pre-forged direction of the billet. 
The hot compression tests were carried out using a Gleeble®1500 servo hydraulic system 
machine (Fig. 1) at constant strain rates of 0.01, 0.1 and 1s”, at temperatures of 768°C 
and 788°C and up to a true strain (¢) of 0.7. The specimens were heated up to the 
compression temperature at 10K/s and were held at this temperature during 5 minutes 
before deformation started. The temperature was controlled by a K type thermocouple 
welded at the middle of the specimen. Three additional thermocouples were used to 
acquire the distribution of the temperature from one of the faces to the centre of the 
specimen. A combination of graphite and molybdenum foils was used to reduce the friction 
between the anvils and the specimen as well as the gradient of temperature along the 
specimen. The deformation for all the tests was controlled by the stroke and measured by 
means of a transverse strain gage located at the middle of each specimen. Furthermore, 
heat treatments to determine the alpha phase transformations were carried out at 768 and N 
788°C at different holding times in the Gleeble®1500 machine in an argon atmosphere “ 
After that, the specimens were quenched in water. Fic 
eff 
pan. Thermocouple (T1) alt 
3. 
Tt 
. for 
the 
Graphite foil+ Mo foil 
St 
Fig 1. Gleeble®1500 machine array 
The specimens were cut parallel to the load axis, mechanical ground and polished. They 
were observed by means of a Scanning Electron Microscope (SEM) in the Backscattered 
Electron mode (BSE) to distinguish the alpha from the beta phase. Around 25 pictures for 
each specimen were taken from the border to the centre of the sample along the mayor 
diameter. The analysis of the pictures was carried out using the software Axio Vs40 v4.4. 
lon Beam Etching (IBE) was used to reveal some aspects of the microstructure, such as 
fine acicular alpha, alpha orientations, etc [7]. 
The B sub-grain size was calculated using the mean linear intercept method according to 
the ASTM Standard [8]. A mean beta sub-grain diameter was determined from the 
measurement in directions both perpendicular and parallel to the compression axis. 
The finite element method (FEM) software DEFORM™ was used to determine the values FE 
of local effective strain (cf) within the deformed specimens. The compression test N 
parameter, the geometry and the gradient of temperature of the sample and anvils as well 8