熔化处理温度对银包套带材中（Bi，Pb）-2223相熔化分解-再形成行为的影响

应用X射线衍射（XRD）和扫描电镜／能谱分析（SEM／EDS）研究了7．5％O2-Ar条件下，熔化处理温度对银包套单芯带材芯部（Bi，Pb）-2223（简称2223）相的分解及再形成行为的影响。结果表明，适当温度下，2223相部分熔化生成一种类似于（Bi，Pb）-2212的液相和碱土铜酸盐（AEC），主要是（Sr，Ca）14Cu24O41（14：24-AEC）和（Ca，Sr）2CuO3（2：1-AEC），对于这一高温超导相的可逆再形成至关重要。随着熔化处理温度的升高，2223相熔化分解生成的液相的成分经历了从介于2223和2212计量比之间向2212，并进一步向2201计量比的演变过程。2223相易于从类似于2212的液相中析出，而从接近2201计量比的液相中更易于生成2212相。2223相从过度熔化生成的液相中再形成经历了两个途径：一是直接从液相中析出，二是由冷却过程初期形成的2212相转变而来。

Effect of Melting Temperature on the Decomposition and Reformation Behavior of(Bi,Pb)-2223 Core in the Ag-sheathed Tape

The effect of melting temperature on the decomposition and reformation of(Bi,Pb)-2223(abbreviated as 2223)phase in a Ag-sheathed mono-filamentary tape under 7.5%O2 flow balanced with argon have been investigated by means of ex-situ X-ray diffraction(XRD)and scanning electron microscopy equipped with energy dispersive spectroscopy(SEM/EDS).It is shown that a partial melting at an appropriate temperature range,which produce a 2212-like melt and alkaline earth cuprates(AEC),especially(Sr,Ca)14Cu24O41(14:24-AEC)and(Ca,Sr)2CuO3(2:1-AEC),as the main decomposition products of 2223,is very important for this high-Tc phase reformation.The melt composition evolved from that between 2223 and 2212 stoichiometries towards 2212,and then to 2201 stoichiometry as melting temperature increasing.It is demonstrated that 2223 could be easily formed from a 2212-like melt but Bi-2212 could be crystallized from a near 2201-like melt.The recrystallization of 2223 from the melt at an excessively high temperature might experience two different routes during the slow-cooling,one is that 2223 reformed directly from the melt and the other iS that 2223 iS transferred from the Bi-2212.