Significant Influences of Hot-Pressure Sintering on Critical Current Density, Grain Connectivity, and Flux Pinning in Me
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ORIGINAL PAPER
Significant Influences of Hot-Pressure Sintering on Critical Current Density, Grain Connectivity, and Flux Pinning in Mechanically Alloyed Nb3Al Superconducting Bulk X. F. Pan 1,2
&
H. Lin 1,2 & T. Xu 1,2 & Z. Yu 3 & Y. Zhang 3 & D. Y. Wang 4 & G. Yan 4 & Y. Zhao 1,2,3
Received: 2 July 2020 / Accepted: 29 July 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The route that combines with the mechanically alloying (MA) and powder-in-tube (PIT) method is thought as a potential way to make cost-friendly Nb3Al superconducting wire, since the MA could produce the high-quality Nb(Al)ss supersaturated solid solution and thus obtain high-Jc Nb3Al superconductor. In order to know the effect of hot-pressure (HP) sintering on superconducting properties and flux pinning of Nb3Al, a series of Nb3Al superconducting bulks annealed at 950 °C for 3 h with different sintering pressure and ball milling time have been prepared in this work. The results suggest that for the mechanically alloyed Nb3Al superconductor, its critical current density (Jc) and superconducting transition temperature (Tc) can be significantly improved by HP sintering. Comparing with the atmosphere pressure (AP) sintering, the Tc, onset and Jc (8 K, 7 T) of HP Nb3Al sample with a milling time of 2 h increase from 15.1 K and 0.56 × 104 A/cm2 to 15.7 K and 6.03 × 104 A/cm2, respectively. Improvement of grain connectivity and flux pinning properties are thought to be mainly responsible to the enhancement of current-carrying ability of HP Nb3Al superconductor. Keywords Nb3Al . Critical current density . Mechanically alloying . Hot-pressing sintering
PACS 74.70.Ad74.25.Ha84.71.Mn81.40.Vw
1 Introduction Since Nb3Al has very well critical current density (Jc), upper critical field (Hc2), and strain tolerance properties, it is thought of as a good alternative to Nb3Sn in application of high-field * X. F. Pan [email protected] * Y. Zhao [email protected] 1
Fujian Provincial Collaborative Innovation Center for Advanced High-Field Superconducting Materials and Engineering, Fuzhou 350117, China
2
Fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials, College of Physics and Energy, Fujian Normal University, Fuzhou 350117, Fujian, China
3
Key Laboratory of Advanced Technology of Materials (Ministry of Education), Superconductivity and New Energy R&D Center, Southwest Jiaotong University, Chengdu 610031, China
4
Western Superconducting Technologies Co. Ltd., Xi’an 710018, China
superconducting magnets [1, 2]. Currently, high-Jc Nb3Al superconducting wires are normally prepared by utilizing the multifilamentary jelly-roll Nb3Al precursor wire and rapid heating, quenching and transformation (RHQT) heattreatment [3, 4]. It is well known that the key of RHQT is continuous heating of the Nb3Al precursor wire up to about 2000 °C by ohmic heating way and immediately cooling up to room temperature to yield Nb(Al)ss supersaturated solid solution; and consequently, the Nb3Al wires with exce
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