The Optimization of Microstructure and Superconducting Properties of Sn Doped Nb3Al Bulks Prepared by Low-Temperature Sintering

In this article, a batch of high-performance Sn-doped Nb 3 Al superconductors is prepared through mechanical alloying and subsequent low-temperature sintering. This article comparatively analyzes the superconducting properties, phase structure, and microstructure of Sn-doped Nb 3 Al under different sintering temperatures and sintering times to determine the most suitable sintering process for Sn-doped Nb 3 Al. The results show that the optimum sintering temperature of Sn-doped Nb 3 Al bulks is 800 °C, with an optimal sintering time of 5 h. The T c value of Sn-doped Nb 3 Al bulk obtained under this sintering condition is 14.8 k, and the value of J c is as high as 6.2 × 10 4 A cm −2 (4.2 K, 5 T). The elevated sintering temperature (900 and 1000 °C) results in significant growth of both Nb 3 Al grain size and Nb 2 Al nanoparticles. This reduces the number of effective pinning centers in the superconducting phase of Sn-doped Nb 3 Al, which severely weakens the flux pinning effect. As a result, the J c performance deteriorates gradually as the sintering temperature increases from 800 to 1000 °C. The extended duration of sintering time results in the formation of sintering holes, which significantly disrupt the continuity of the Nb 3 Al superconducting phase matrix and degrade its superconducting properties.