Equiaxial nano-crystals Nb3Al superconductor prepared by optimized mechanically alloying

The Preparation of a Challenging Superconductor Nb3Al by Exploiting Nano Effect

“…The sample, which was sintered under 1400 • C for 10 h with r = 3.0 (25 mol% Al), has a relatively high transition temperature T c = 16.8 K (inset illustration). Nevertheless, the boundary is different compared to the experiments of Abe et al [41] and Zhang et al [13]. However, the value of T c (16.8 K) is comparable to that of Nb 3 Al samples prepared by using the RHQT (16.8 K ~17.3 K) method [4] and higher than the transition temperatures of Nb 3 Al samples synthesized by using the MA method (15.8 K) [13,42].…”

“…The microstructure and the elemental composition of the as-prepared Nb 3 Al samples were analyzed using SEM and EDS. As can be seen from Figures S4 and S5 [41] and Zhang et al [13]. However, the val of Tc (16.8 K) is comparable to that of Nb3Al samples prepared by using the RHQT (16.8 ~ 17.3 K) method [4] and higher than the transition temperatures of Nb3Al samp synthesized by using the MA method (15.8 K) [13,42].…”

“…As can be seen from Figures S4 and S5 [41] and Zhang et al [13]. However, the val of Tc (16.8 K) is comparable to that of Nb3Al samples prepared by using the RHQT (16.8 ~ 17.3 K) method [4] and higher than the transition temperatures of Nb3Al samp synthesized by using the MA method (15.8 K) [13,42]. Unlike other pretreatment methods, which increase the specific surface area of N and Al at the same time, the pretreatment method in this paper increased only the speci surface area of Nb.…”

“…Planar faults within the {100} layers would compensate for deviations from stoichiometry because none of the {100} layers in the A15 structure have the stoichiometric composition [41]. The A15 phases reported by Abe et al can correspond well to the Nb-Al phase diagram, in contrast to the work by Zhang et al [13]. This may be due to the formation of a Nb/Al solid solution after ball grinding in Zhang's work, in which the synthesis mechanism is inconsistent with the phase diagram; see Figure S1.…”

“…However, the synthesis of pure Nb 3 Al is not straightforward because of the high melting point of Nb, the narrow phase width of Nb 3 Al, and a peritectic decomposition at 1940 °C, as shown in the Al-Nb phase diagram in Figure S1 . The so-called low-temperature approaches are involved in the technologies of JR (jelly roll) [ 9 , 10 ], RIT (rod-in-tube) [ 11 ], CCE (clad-chip extrusion) [ 12 ], the most widely used MA (mechanical alloying) [ 13 , 14 ], etc. The T c of samples obtained using these methods is far from the theoretical value, and J c decreases rapidly in high fields under low temperatures [ 15 ].…”