Effect of Impurities on Polycrystal Anelasticity

Abstract

Anelastic relaxation of rock can cause seismic low velocity and high attenuation in the upper mantle (e.g., Jack-

Effect of Melt on Polycrystal Anelasticity

“…The previous samples #41 and #42 were prepared similarly to the present samples (#50 and #h21) by supersolidus annealing but without the second stage annealing and hence might have a connected network of solidified melt at the beginning of the first mechanical test. In contrast, previous samples #44 and #197 (Takei, 2022; Yamauchi & Takei, 2016) had dispersed diphenylamine grains similar to the present samples, but were prepared by subsolidus annealing without any experience of partial melting. Comparison between the present data and the previous data from these samples enables us to investigate the hysteresis effect of partial melting, which was sometimes observed at subsolidus temperatures and prevented detailed analysis of the premelting effect (Yamauchi & Takei, 2016).…”

“…Third, if the peak growth was caused by impurities, the temperature T e = 316 K would not have played an important role. Indeed, the impurity-induced peak reported by Takei (2022) did not depend on T/T e . In contrast, the diphenylamine-induced peak does depend on T/T e (Figure 9a).…”

“…The results of sample #42, the 1st temperature cycle of #50, and the 2nd cycle of #50 are summarized in the 5th, 6th, and 7th lines, respectively, of Table 5. For comparison, similar analyses were performed on samples #44 (Yamauchi & Takei, 2016) and #197 (Takei, 2022), which had not experienced partial melting and hence were not affected by the hysteresis effect. The results are plotted in Figure 9a in terms of $${{\Delta }}_{P}=\sqrt{2\pi }{A}_{P}{\sigma }_{P}$$ (black and gray symbols).…”

“…Second, if the measured anelasticity was controlled by impurities, the property is expected to change by purification. Indeed, some abnormal mechanical and grain growth behavior exhibited by a certain lot of borneol was no more observed after the purification of borneol by recrystallization (Takei, 2022). However, when diphenylamine is mixed to the purified borneol, the subsolidus behavior of anelasticity was reproduced very well (Figures 9 and 10 in Takei, 2022), indicating that the subsolidus change is an intrinsic behavior of the borneol + diphenylamine binary eutectic system.…”

“…First, if the subsolidus peak growth was caused by impurities, the peak growth would have occurred without diphenylamine. Takei (2022) showed that the mechanical and grain growth behavior of borneol can be significantly affected by impurities, but the behavior is similar within the same lot. Therefore, borneol is considered to be chemically homogeneous within each lot.…”