原位粉末装管法37芯MgB2线材的制备及性能研究

Fabrication and properties of 37-filaments MgB2 superconducting wires by in-situ powder-in-tube method

摘要:

传统的Cu包套原位粉末装管法(in situ PIT)制备多芯MgB₂超导线材时,易于出现断芯、断线现象。针对一问题,本实验中以强度较高的梦乃尔合金(Monel 400)作为包套材料,以旋锻、拉拔、轧制及中间热处理相结合的加工手段成功的制备出直径Φ1.0 mm、37芯结构的多芯MgB₂超导长线材。微观结构分析表明多芯线材中MgB₂芯丝及替换芯丝等亚组元的分布较为规整,阻隔层未出现明显破损现象,最终线材中MgB₂超导芯丝的平均直径约80 μm。室温拉伸性能显示热处理前MgB₂线材的屈服强度为759 MPa,热处理后的线材为248 MPa。4.2 K、4 T下,线材的临界电流密度J_c达到2.31×10^₅ A.cm^_-2,工程临界电流密度达到3.16×10^₄ A.cm^_-2。

Abstract:

The filament fractures or wire breaks in multi core MgB₂ wire was appeared frequent while using the traditional in-situ powder in tube (PIT) method with Cu as the sheath material. For this problem, the 37 filament MgB₂ long wires with the diameter of 1 mm, sheathed with higher strength Monel alloys (Monel 400) is fabricated with compound fabrication process including rotary swage, drawing, rolling and middle annealing heat treatment。Microstracture showed that the sub component including MgB₂ filament and NbCu replacement is uniformly distributed and the Nb diffusion barrier is no breaking points. The mean diameter in MgB₂ filament is only 80 μm in final wires. The yield strength is around 759 MPa. for the as-drawn wire and 248 MPa for the sintered wire. The critical current density (J_c) and engineering current density (J_e) are arrived 2.31×10^₅ A.cm^_-2 and 3.16×10^₄A.cm^_-2 at 4.2 K、4 T respectively.