An Experimental and Theoretical Multi-Mbar Study of Ti-6Al-4V

Abstract

We report results from an experimental and theoretical study of the room temperature (RT) compression of the ternary alloy Ti-6Al-4V. In this work, we have extended knowledge of the equation of state (EOS) from 40 GPa to 221 GPa, and observed a different sequence of phase transitions to that reported previously for pure Ti.

Titanium Alloys at Extreme Pressure Conditions

“…There is good agreement between the Chesnut et al and our (Tegner et al, n.d.) measurements (both using a methanol: ethanol PTM), but not with the Halevy et al measurements (there was no mention of a PTM being used in their study). We measured the P → = 31.2 GPa, and an isothermal bulk modulus of K = 115  3 GPa and pressure derivative of K' = 3.22  0.22 after fitting a Vinet EOS (Vinet et al, 1987) to the data (Tegner et al, 2011). The volume change across the phase boundary was measured to be less than 1%, in agreement with the previous methanol: ethanol study (Chesnut et al, 2008).…”

“…It is clear from figure 3 that both the  and  phases coexist over a large pressure range, of the order of 10 GPa (between ~ 32.7 GPa and ~ 44 GPa). We observed similar behaviour for Ti-6Al-4V embedded in methanol: ethanol and mineral oil, and also for an experiment with no PTM (Tegner et al, 2011). For Ti-6Al-4V embedded in methanol: ethanol, we decompressed our DAC from 75 GPa to ambient and observed the phase to gradually revert back to the  phase.…”

“…As the most prevalent Ti alloy currently in commercial and industrial usage, it is perhaps not surprising that Ti-6Al-4V has received the most attention of all the Ti alloys at high pressure (Rosenberg & Meybar, 1981;Gray et al, 1993;Cerreta et al, 2006;Chesnut et al, 2008;Halevy et al, 2010;Tegner et al, 2011;Tegner et al, n.d). The alloying of a metal can have substantial effects on its properties, which of course is the desired effect, and so it is important that we understand how the alloy responds to extremes of pressure.…”

“…In the most recent DAC study of Ti-6Al-4V, conducted by two of us (MacLeod and Cynn), powdered polycrystalline samples were embedded in a variety of PTMs to investigate the effects of the pressure environment on the RT    phase transformation (Tegner et al, 2011;Tegner et al, n.d.). ADXD data were collected at the High Pressure Collaborative Access Team (HP-CAT) beamline 16-IDB at the Advanced Photon Source (APS) in Chicago, for Ti-6Al-4V samples embedded in neon, 4:1 methanol: ethanol and mineral oil.…”

“…4. The P-V plot for Ti-6Al-4V in a methanol: ethanol PTM (Chesnut et al, 2008& Tegner et al, 2011 and also for an unspecified PTM (Halevy et al, 2010). (Tegner et al, n.d.), Ti with no PTM (Velisavljevic et al, n.d.) and Ti-Beta-21S in a methanol: ethanol PTM .…”