Multifilamentary, in-situ Route, Cu-stabilized MgB2 Strands

Transport critical current densities and n-values were measured at 4.2 K in fields up to 15 T on 7, 19, and 37-stack multifilamentary MgB2 strands made using an in-situ route. Some strands included SiC additions (particle size 30 nm), while in others Mg-rich compositions were used. Two basic multifilamentary variants were measured, the first had Nb filamentary barriers, the second had Fe filamentary barriers. All samples incorporated stabilizer in the form of Cu 101. Simple, one-step heat treatments were used, with temperatures ranging from 700-800C, and times from 10-30 minutes. Transport critical current densities of 1.75 x 105 A/cm2 were seen at 4.2 K and 5 T in 37 stack strands.Comment: 10 pages, 3 figs, 2 table

Hydrostatic extrusion of UFG aluminium

The feasibility of hydrostatic extrusion (HE) of ultrafine grained (UFG) AA1070 has been investigated. The UFG material was produced by equal channel angular pressing (ECAP) using a scaled-up, two-turn, S-shape channel. Four passes of ECAP were followed by three passes of HE, which reduced the billet cross-section from a 26 x 26 mm2 square to 5 mm diameter round section. The average grain size of 0.6 micron after ECAP was reduced to 0.4 micron by HE. The strength and hardness increased by ECAP were further increased by HE. Ductility was reduced by ECAP, however, it remained constant during HE. The suggested sequence of operations seems to be a feasible option for producing UFG billets for shaping elongated products