実験報告書様式（一般利用課題・成果公開利用）

MLF Experimental Report

提出日 Date of Report
March 21, 2013

課題番号 Project No.

装置責任者 Name of responsible person

2012B0108

Kazuya Aizawa, Stefanus Harjo

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Thermal Strain Exerted on Superconductive Filaments in BL19: TAKUMI
実施日 Date of Experiment
Practical Nb3Sn and Nb3Al Strands
実験責任者名 Name of principal investigator

23 – 27 Dec, 2012

Kozo Osamura
所属 Affiliation
Research Institute for Applied Sciences
試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.

Two types of SC strands were examined. Nb3Sn strand was fabricated by Hitachi cable for ITER
project, in which 11,000 SC filaments were embedded in the bronze matrix and surrounded by Nbbarrier and Cu stabilizer. The original composition of bronze was 15.5wt%Sn-0.3wt%Ti.
According to the preliminary electron microscope analysis, the Sn concentration of Cu-Sn matrix
was 0.9– 1.1wt% Sn after the fully reacted state. Nb3Al strand was fabricated by Hitachi cablethrough Jerry Roll method, in which 90 SC filaments were embedded in Cu matrix.

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

The diffraction measurements were carried out at TAKUMI of J-PARC, where the pulsed
neutrons with wavelength region between 0.06 and 0.2 nm were utilized. The diffracted beams
were detected by means of two detector banks consisting of 3He detectors, which were equipped at
two orthogonal positions to the incident beam. The south data bank accumulated the diffracted
neutrons parallel to the strand axis, but another north one accumulated the diffracted ones
transverse to the strand axis. In principle, each data bank was able to accumulate two dimensional
data with respect to wavelength and diffraction angle. In order to measure the thermal strain atelevated temperatures, the bundle of short samples was put in the evacuated electric furnace, which
was equipped at the center of goniometer. The simultaneous experiments of tensile test anddiffraction were carried out at room temperature by using the specially designed load frame, which
was equipped at the center of goniometer. The Nyilas type extensometer was attached to thesample to measure external strain.
12. 実験方法及び結果（つづき） Experimental method and results (continued)

By using the electric furnace, the temperature dependence of thermal stains exerted on SC
filaments was measured along both axial and transverse directions as shown in Fig. 1. Here theroom temperature data are added in the figures. The axial thermal strain near room temperature
was negative, that means compressive strain. It decreased with increasing temperature and became
zero. Then the sign of thermal strain turned to positive, it means tensile. It tended to saturate athigh temperature. On the other hand, the transverse thermal strain was compressive in the wholetemperature range and gradually decreased with increasing temperature for Nb3Sn strand. In thecase of Nb3Al strand, the behavior of axial thermal strain was similar to the change for Nb3Sn as
shown in Fig.1(b). At room temperature, the axial strain was compressive. With increasing
temperature, the thermal strain became tensile and saturated. The transverse thermal strains atroom temperature were scattered, but their average was compressive. It increased and turned totensile with increasing temperature.
0.1

0.15

Nb3Al heating

Nb3Sn heating
0.1

ATNb3Al (%)

ATNb3Sn (%)

0.05

0.05
00

-0.05
-0.1
-0.15
200

300

400

500

600

700

axial
trnasverse
axial (RT)transv (RT)

-0.05

axial
transverse
axial (RT)transv (RT)-0.1200800300400500600700800

T (K)

T (K)

(a) Nb3Sn(b) Nb3Al

Fig. 1 Change of thermal strain as a function of temperature for Nb3Sn and Nb3Al strands.

Their temperature dependence was numerically evaluated by means of iteration method. As awhole, it has been established that the temperature dependence of thermal strain can be well
reproduced by the numerical calculation proposed here. It was pointed out that the thermal strain
on SC filaments is affected by the creep phenomenon at high temperatures above a thresholdtemperature.

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