Large improvement in high-field critical current densities of Nb3Al conductors by the transformation-heat-based up-quenching method
Large improvement in high-field critical current densities of Nb3Al conductors by the transformation-heat-based up-quenching method
复制标题
DOI：
10.1088/0953-2048/13/10/101
复制
发表时间：
2000-10
影响因子：
3.6
通讯作者：
T. Takeuchi;N. Banno;T. Fukuzaki;H. Wada
中科院分区：
文献类型：
--
作者：
T. Takeuchi;N. Banno;T. Fukuzaki;H. Wada
对多丝Nb/Al复合丝进行快速加热淬火得到的bcc过饱和固溶体Nb(Al)ss，在转变为A15 Nb3Al相之前，晶体结构由无序变为有序。bcc相的这种排列似乎是导致A15相堆积错误的原因，这种错误降低了Nb3Al在高场中的临界温度（Tc）、上限临界磁场（Bc2），从而降低了临界电流密度（Jc）。热处理温度在1000°C左右，比常规相变温度高约200°C，会抑制有序，并产生一种新的现象，称为“基于相变热的上淬”（TRUQ）。TRUQ的特点是通过相变热使bcc相自热，并通过整个复合丝的长度将其转变为Nb3Al。随后的800℃退火增强了Nb3Al相的长程有序性，并显著提高了Nb3Al导体的高场临界电流密度。
The bcc supersaturated solid solution Nb(Al)ss obtained by rapid heating and quenching of a multifilamentary Nb/Al composite wire has shown a crystal structure change from a disordered to an ordered structure before transforming to the A15 Nb3Al phase. Such ordering of the bcc phase seems to be responsible for the A15 phase stacking faults that depress the critical temperature (Tc), the upper critical magnetic field (Bc2) and, hence, the critical current density (Jc) of Nb3Al in high fields. A heat treatment around 1000 °C, higher than conventional transformation temperatures by about 200 °C, suppresses the ordering and yields a new phenomenon termed the `transformation-heat-based up-quenching' (TRUQ). TRUQ is characterized by the self-heating of the bcc phase by the transformation heat, which propagates through the whole length of a composite wire and transforms it to Nb3Al. A subsequent annealing at 800 °C enhances the long-range ordering of the Nb3Al phase and drastically improves the high-field critical current densities of the Nb3Al conductors.