Development of cryogenic tensile testing apparatus for lattice strain measurement using synchrotron radiation for REBCO composite conductors

菅野 未知央*; 町屋 修太郎*; 菖蒲 敬久; 城 鮎美*; 梶原 堅太郎*; 中本 達志*

Superconductor Science and Technology, 33(8), p.085003_1 - 085003_10, 2020/08

https://doi.org/10.1088/1361-6668/ab953e

REBaCuO-delta (REBCO) composite tapes are candidate conductors for future accelerator magnets. Given that REBCO is a brittle oxide film, stress/strain management is important in the mechanical design of a magnet. Therefore, the strain state of a superconducting film should be predicted under various operating conditions. A quantum beam is a useful tool in evaluating the strain state of a superconducting material in a composite conductor. Although various cryogenic tensile testing machines, in combination with neutron beam and synchrotron radiation, have been developed, they are not necessarily optimized for measuring highly textured materials such as REBCO films. This study reports a novel cryogenic tensile testing apparatus that can be used at the beamline of a synchrotron radiation facility. In this system, a superconducting tape is cooled using a Gifford-McMahon (GM) cryocooler through 2.5 m long thermal links made of 5 N high-purity aluminum. This enables a compact cryogenic loading system that can be mounted on the goniometer of a beamline. Lattice strain measurements using synchrotron radiation were conducted at 40 K, 77 K, and 300 K for a commercially available (Y,Gd)BCO coated conductor at BL28B2 in SPring-8. The onset strain of film fracture determined from the lattice strain measurement at 77 K agreed well with the irreversible strain of critical current at the same temperature. The residual and fracture strain of the (Y,Gd)BCO film at 77 K was evaluated as well.

正方晶ZrOを含むジルカロイ酸化膜の特性; ジルカロイ-4管の酸化膜

本橋 治彦; 古田 照夫

JAERI-M 83-132, 15 Pages, 1983/08

JAERI-M-83-132.pdf:0.66MB

ジルカロイ-4管が水素・水蒸気の混合気流中、1000Cで酸化した時に生成する層状酸化膜の特性を20C~1300Cの温度でX線回折法により調べた。室温におけるX線回析図形の解析から、正方晶ZrOを含む層状酸化膜中の単斜晶ZrOは340の小さな結晶子となり0.03%の大きな格子歪を持ちそして111の格子面間隔が標準物質より0.7%大きくなっていることを明らかにした。また高温X線回折から正方晶ZrOを含む層状酸化膜中の単斜晶ZrOはゆるやに相変化を起こすことがわかった。この相変化の起こる温度は正方晶ZrOを含まない酸化膜中の単斜晶ZrOの相変化温度より低くなっている。これらの事実から正方晶ZrOを含む層状酸化膜の生成は酸化膜の結晶子の微細化と大きな格子歪か生じる事と相関性があることを明らかにした。