実験報告書様式（一般利用課題・成果公開利用）（ ※本報告書は英語で記述してください。ただし、産業利用課題として採択されている方は日本語で記述していただいても結構です。 ）MLF Experimental Report

提出日 Date of Report

課題番号 Project No.

装置責任者 Name of responsible person

2017A0032

Stefanus Harjo

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Measurement of anisotropy of residual stress and strain in

TAKUMI / (BL19)

Ni-based superalloys due to precipitation misfit and plastic strain

実施日 Date of Experiment

実験責任者名 Name of principal investigator

April 2 - April 5

Tokujiro Yamamoto
所属 Affiliation
Utsunomiya University
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.
Change in the diffraction peaks of nickel-based superalloy (PWA1480) specimens was examined withapplying tensile stress at high temperature. The specimens were composed of the FCC γ phase and L12 γ' phase.
The γ' phase was precipitated in the γ phase with keeping crystallographic orientation between the γ phase byaging at high temperature. The morphology of the γ matrix and the γ' precipitates in the specimens is
schematically illustrated in Fig. 1. When the longitudinal direction of a round bar single crystal specimen before
aging is [001]γ, three types of the thin plate-like γ
channels are formed between the γ' precipitates.
Here, the γ channel parallel to (001)γ (also parallelto (001)γ') is denoted as the (001) γ channel, forexample.
The lattice parameters of the γ and γ' phases area0 and a, where a is slightly smaller than a0.
Because of the misfit between the γ matrix and theγ' precipitates, residual stress exists in the specimen.
According to analysis using micromechanics,
tensile stress is applied to the thickness direction
and compression stress is applied perpendicular to
the thickness direction by precipitation of the γ'phase.

Fig. 1. Schematic illustration of the experimental setup
for neutron diffraction experiments.

1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 round bar single crystal specimens were mounted to a tensile testing machine installed in BL19 Takumi
beamline, so that tensile stress can be applied along the longitudinal direction, i.e. [0 0 1]γ. The incident neutron
beam was radiated along [1 0 -1]γ. The specimens were rotated to detect 0 0 l and h 0 0 diffraction peaks (seeFig. 1). Neutron diffraction patterns were measured using a time-of-flight method at room temperature, 673 Kand 973 K. Measurements were also performed at 973 K with applying tensile stress to the specimens. The
maximum tensile strain was 8%. Diffraction peaks of a pure Ni single crystal was also measured without
applying stress at room temperature as a reference. 0 0 2 and 2 0 0 peaks composed of the γ and γ' phases, while
0 0 3 and 3 0 0 diffraction peaks came only from the γ' phase.
Fig. 2 shows the profiles of the 0 0 3 and 3 0 0 diffraction peaks as a function of the specimen temperature.
Both the lattice spacing of (0 0 3)γ' and (3 0 0)γ' increased with increasing the temperature because of thermal
expansion of the specimen.
After heating up to 973 K, tensile stress was applied to the specimen along [0 0 1]γ orientation, and followedby unloading. Fig. 3 shows the profiles of the 0 0 3 and 3 0 0 diffraction peaks at 973 K after unloading as afunction of the plastic strain introduced in the specimen. The lattice spacing of the (0 0 3)γ' increased withincreasing the plastic strain, while that of the (3 0 0)γ' decreased. It represents that tensile and compression stress
was applied along [0 0 1] and [1 0 0] orientation of the γ' precipitates, respectively.
It should be noted that the width of the 0 0 3 diffraction peak increased more rather than the peak position
upon tensile testing. Meanwhile, the width of the 3 0 0 diffraction peaks also increased. These results indicatethat a certain amount of plastic strain was introduced in the γ' precipitates.

Fig. 2. Change in the lattice spacing of (a) (003)γ'

Fig. 3. Change in (a) 003 and (b) 300 diffractionand (300)γ' plane before loading as a function ofpeaks of the γ' phase at 973 K after unloading as athe specimen temperature.

function of the plastic strain introduced in thespecimen.

22. 実験方法及び結果（つづき） Experimental method and results (continued)
For the 0 0 2 and 2 0 0 diffraction peaks, the lattice spacing of the (0 0 2) and (2 0 0) planes of the γ matrixand γ' precipitates also increased by thermal expansion, as shown in Fig. 4.
However, even though plastic strain was introduced in the specimen, the change in the position of the 0 0 2
and 2 0 0 diffraction peaks, which is composed by both the γ matrix and γ' precipitates, was smaller than that of
the 0 0 3 and 3 0 0 peaks of the γ' precipitates as shown in Fig. 5.
Bruno et al. (2003) analyzed the 0 0 2 and 2 0 0 diffraction peaks, assuming that those peaks were composedof three peaks. However, according to our analysis using micromechanics, the γ matrix is also affected by theresidual stress caused by the misfit. For example, the 0 0 2 diffraction peak should be composed by the peaks
caused by the following four lattice planes:(0 0 2)γ with tensile stress in the (0 0 1) γ channel,(0 0 2)γ with compression stress in the (1 0 0) γ channel,(0 0 2)γ with compression stress in the (0 1 0) γ channel,(0 0 2)γ' with tensile stress in the γ' precipitates
Therefore, the 0 0 2 diffraction peaks is decomposed to the four peaks by the (0 0 2)γ and (0 0 2)γ' planes, andthe 2 0 0 diffraction peaks is also decomposed to the four peaks by the (2 0 0)γ and (2 0 0)γ' planes. Theasymmetry and tails of the 0 0 2 and 2 0 0 diffraction peaks is agree with the decomposed four peaks above
mentioned.
Our micromechanics analysis revealed that the change in the lattice spacing for (0 0 2)γ with tensile andcompression stress is about 3%. The composition of the four diffraction peaks in the asymmetrical 0 0 2 and 2 00 diffraction peaks will be examined, taking the change in the lattice spacing into consideration.

Fig. 4. Change in the lattice spacing of (a) 002 andFig. 5. Change in (a) 002 and (b) 200 diffraction200 diffraction peaks before loading as a function

peaks at 973 K after unloading as a function of theof the specimen temperature.

plastic strain introduced in the specimen.

3