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
2017/5/12

課題番号 Project No.

装置責任者 Name of responsible person

2016B0114

Kazuya Aizawa

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Phase Transformation and Texture Development during Hot

BL19

Deformation in High-Strength Ti Alloys

実施日 Date of Experiment

実験責任者名 Name of principal investigator

2017/2/19-21, 23

Nobuhiro Tsuji
所属 Affiliation
Kyoto 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.
Ti-6Al-4V (mass%) alloy

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.

Titanium (Ti) and Ti-alloys are widely used in aeroplane and space applications due to their excellent
strength to weight ratio, high-temperature strength, and corrosion resistance. The most widely usedhigh-strength  +  type Ti alloy is Ti-6Al-4V having  phase of hexagonal close-packed (HCP)
structure and  phase of body centered cubic (BCC) structure.

Aeroplane parts of Ti-6Al-4V alloy are

fabricated through hot forging at high temperatures, i.e., thermomechanical processing, after melting
and casting.

The hot deformation (forging) is carried out in  single-phase region as well as in + 

two-phase region, so that complicated microstructures that affect their mechanical properties areobtained.
In the present experiment, the transformation behaviors and development of textures in the Ti-6Al-4V
alloy were studied by in-situ neutron diffraction using the newly developed thermomechanicalprocessing simulator (Figure 1).

This simulator can heat specimen up to 1200 °C by induction heating

system under vacuum condition or gas atmosphere, and can apply precisely controlled compression
deformation at a maximum deformation rate of 100 mm s-1 with a maximum load of 30 kN.
1

2. 実験方法及び結果（つづき） Experimental method and results (continued)
The cylindrical specimens 11 mm inheight and 6 mm in diameter were
heated up to the temperatures ranging
from 900 °C to 1050 °C and held
isothermally for 600 s.
specimens

wereThen, thedeformedincompression up to 50 % reduction inheight, and cooled immediately at acooling rate of 1 °C.
thermomechanical

During theprocessing,

thepulsed neutron beam was irradiated tothespecimenfrom

thedirection

perpendicular to the compression

Figure 1.

(a) Appearance of the thermomechanicalprocessing simulator installed on BL19 TAKUMI, and (b) aschematic illustration and snap shots in a hot-compression
experiment in the simulator.

axis, and the diffracted neutron beam was corrected by the two time-of-flight (TOF) detectors whichwere located at the positions perpendicular to the incident neutron beam, i.e., the diffracted planes inthe specimen were parallel to the compression axis.
Figure 2 shows neutron diffraction profiles obtained (a) before the compression and (b) at the laterstage of the compression, respectively.
using Z-Rietveld software.

The diffraction profiles were analyzed by Rietveld method

Five peaks in  phase ((10-10), (0002), (10-11), (10-12), (2-1-10)) andthree peaks in  phase ((110), (200), (310)) were used to investigate the changes in orientation
during the hot compression.
Figure 3 summarizes the relative intensity of several diffracted planes in (a)  phase and (b) I0 and I1 indicate the intensities before the compression and at the later stage of theα(10-10)α(0002)α(10-11)α(10-10)α(0002)α(10-11)β(110)β(200)α(10-12)β(200)α(10-12)α(10-13), β(211)
β(220)β(310)

Intensity(b)α(2-1-10)β(310)

Intensity(a)β(110)The intensity of (0002) plane and (110) plane increased after the hotα(2-1-10)compression, respectively.

α(10-13), β(211)

phase.

TOFFigure 2 Neutron diffraction profiles obtained (a) before the compression and (b) at the later stageof the compression, respectively.

22. 実験方法及び結果（つづき） Experimental method and results (continued)compression.

This indicates that (0002) and (110) planes tended to rotate parallel to thecompression direction.

At the deformation temperature,  phase (referred to as primary ) and 

phase exist, and a volume fraction of  phase is about 70%.

But almost all  phase transform to phase (referred to as secondary ) after cooling to room temperature. Through the conventional
microstructural observation at room temperature, it is very difficult to understand the orientation changeof  phase during the hot deformation.

The present in-situ neutron diffraction analysis during the hotcompression successfully revealed that (110) plane was rotated perpendicular to the compression
direction as well as (0002) plane.
(a)

(b)
1.8

1.4

1.6

1.2

1.4
1.0

1.0

I1/I0

I1/I0

1.2

0.8

0.80.6

0.6

0.4

0.4
0.2

0.2
00(0002) (10‐10) (10‐11) (10‐12) (2‐1‐10)

(110)

(200)

(310)

Figure 3 The relative intensity of several diffracted planes in (a)  phase (HCP) and (b)  phase(BCC).

I0 and I1 indicate the intensities before the compression and at the later stage of thecompression, respectively.

3