Anelastic Relaxation Measurements in Nb-46wt%Ti Alloys with Interstitial Solutes in Solid Solution

Abstract

Anelastic relaxation measurements were performed in a Nb-46wt%Ti alloy, in the temperature range of 300 to 700 K, using a torsion pendulum operating at an oscillating frequency near 2.0 Hz. The samples were measured in different conditions: cold worked, annealed in ultra-high vacuum and doped with several quantities of nitrogen. The relaxation spectra obtained were resolved into their component peaks, corresponding to the different kinds of interaction of the interstitial solutes with the metallic matrix. The relaxation parameters of each process were calculated using Debye’s elementary peaks.

Internal Friction and Microstructure of Ti and Ti-Mo Alloys Containing Oxygen

“…Grandini et al studied the stress induced ordering of oxygen atoms in Nb-Ti [61][62][63][64][65] and Ti-based alloys [66,67] and reported the activation energy of 1.23 eV for the stress induced ordering of oxygen atoms around titanium atoms. The chemical and gas analysis show ( Tables 1 and 2) that the samples contain mainly titanium and small quantities of impurities, and a certain amount of oxygen (0.14 wt.%) and nitrogen (0.02 wt.%).…”

Diffusion of Interstitial Solutes in Nb-46wt% Ti Alloys Measured by Mechanical Spectroscopy

“…The peaks in the internal friction curve and a step in the frequency curve are demonstrated in Fig. 1 [7]. These are signatures of relaxation processes of Snoek's type, due to stress-induced ordering of interstitial atoms around the atoms of the alloy [2].…”

“…The following samples were produced: cold worked (NbTi #1 sample); annealed in ultra-high vacuum of 10 -8 Torr at 1470K for four hours (NbT i#2 sample); charged with nitrogen, subsequent to vacuum annealing, at partial pressures of 1 x 10 -7 (NbTi #3 sample), 5 x 10 -6 (NbTi #4 sample), and 5 x 10 -5 Torr (NbTi #5 sample) at 1470K for two hours. Table 2 shows the analysis of the oxygen and nitrogen content in the conditions mentioned above made using LECO TC-400 equipment [7]. Measurements of internal friction and frequency were carried out as a function of temperature by means of an inverted torsion pendulum between 300 K and 700 K. A heating rate of 1.0 K/min and a frequency of approximately 2.0 Hz were employed.…”

Anelastic spectroscopy in Ti-13V-11Cr-3Al alloy

“…The activation enthalpies for these relaxation processes were obtained from the previous papers of Weller [15], Almeida et al [16] and Grandini et al [17]. It can be noticed in these figures that the continuous curves, which are the sum of the constituent peaks, fit (fully circle) the experimental points quite well.…”