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Re Effect-MoRe Welds-3

2. Mo-Re alloys with two-phase precipitation : Mo-47 wt.% Re and Mo-50 wt.% Re

2-1. Mo-47 wt.% Re

Characteristics of Mo-47%Re alloy by Indentation and Microstructural Method*:

*Unpublished work :

M. I. Danylenkoa, T. Kadokura

b and K. Okamoto

b , A. V. Krajnikov

a, F. Morito

a, c,

a Institute for Problems of Materials Science, Kyiv, Ukraine b Allied Materials Corp. (ALMT), Toyama, Japan

c MSF Laboratory, Moriya, Japan

TEM observation & Microhardness : M. I. Danylenkoa

Fabrication of PM Mo-47%Re sheet : T. Kadokurab and K. Okamoto

b

Part I : as-rolled Mo-47%Re sheet

Material and experiment

Fabrication of PM Mo-47%Re sheet

Mo-47%Re alloy was produced by powder metallurgy. The purity of the starting raw powder

was 99.9 % or more both in Re and Mo. Re content reduced from 49.0 % in as-sintered state

to 47.0 % in the 1.0 mm sheet. After mixing raw powders were followed by pressing (CIP),

sintering in hydrogen, sintering in vacuum, hot rolling and annealing, finally the deformed

ingot of 110 L x 50 W x 25 mm H was manufactured. Then the processing of heating and

rolling at ambient temperature was repeated as follows to make Mo-Re sheet with a suitable

thickness.

Fig. 1 Sample of 1.0 mm thick Mo-47%Re sheet (Mo.jpg)

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Total (General ) accumulated Reduction(TR) <Rolling Ratio>

TR =94.0% by Hot Rolling (25-1.5mm) with Intermediate Annealing

Step 1 : TR=68.0% (25 - 8.0 mm)

Step 2 : TR=81.25% (8.0 - 1.5 mm)

Cold Rolling with Intermediate Annealing

Step 3 : TR=33.3% (1.5- 1.0 mm)

Step 4 : TR=10.0% (1.0-0.9 mm)

Step 5 : TR=11.1% (0.9-0.8 mm)

Step 6 : TR=37.5% (0.8-0.5 mm)

Step 7 : TR=20.0% (0.5-0.4 mm)

Step 8 : TR=32.5% (0.4-0.27 mm)

Table 1 Chemical content of PM Mo-47%Re

Element (ppm) C O N Al Ca Cr Cu Fe Mg Mn Ni Si Sn W

As-sintered 20 <10 <10 <5 <1 23 <1 6 <1 <1 <3 <20 <10 10

Sheet 10 <10 <10 <5 <1 2 1 5 <1 <1 3 <20 <10 10

Chemical content of 1.0 mm thick Mo-47%Re sheet is shown in Table 1. Microstructure was

examined by optical microscopy and transmission electron microscopy. Indentation test was

carried out by the indentator of 40 gf or 100 gf in IPMS. Vickers hardness was measured by

10 kgf indebtator in ALMT. Tensile properties of the as-rolled 1.0 mm thick sheet were tested

at RT, 773 K and 1273 K.

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Result and discussion

Fig. 2. Microstructure of (a) 1.0, ( b) 0.5, (c) 0.27 mm thick sheet in the as-rolled Mo-47%Re

alloys.

(a)

(a)

(b)

(c)

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(a) Mo-47Re : t=1.0mm, as-rolled

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(b) Mo-47Re : t=0.5mm, as-rolled

(b) Mo-47Re : t=0.27mm, as-rolled

Fig. 3. 3D photos of (a) 1.0, ( b) 0.5, (c) 0.27 mm thick sheet in the as-rolled Mo-47%Re

alloys.

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The results of microhardness measurement are summarized in Fig 3. The hardness increases

with deformation in a range of t=1 – t=0.8 (black line with down-triangles). At higher

deformation the level of hardness is stabilised. Simultaneously the hardness of different part

of the surface becomes non-uniform. The parts with lower hardness co-exist with other parts

demonstrating higher hardness (see blue up-triangles and red dots)

Fig. 4. Microhardness as a function of sheet thickness (P= 40g or 100g)

It is noteworsey that each sheet sample had different processing with extent of rolling

reduction, rolling deformation and so on. As a result, we could measured the microhardness

data as in Fig. 4.

Mo-47 wt.% Re hardens by the two-phase type Mo-Re alloys. Tendency of precipitation

hardening was similar to solution hardening (Fig. 5). Mo-50 wt.% Re also shows the same

tendency of an increase of hardening.

1,0 0,8 0,6 0,4 0,2

610

620

630

640

650

660

670

680

690

700

710

720

730

Mic

roh

ard

ne

ss

, k

G/m

m2

t

Soft phase

Middle phase

Hard phase

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Fig. 5. Hardness of Mo-Re alloys annealed at 1873 K for 3.6 ks.

As for lower and higher hardness among more thiner sheet, it is found that two or three phases

with different hardness were co-exist. The area with middle hardness means the co-existing of

both area.

For example, it is possible to observe several ppts along grain boundaries on TEM 8840854

(enlarged one of 5840855 ) in TD plane of t=0.27 mm sheet.

The diffraction pattern shows that they are sigma-phases along the texture boundary between

matrix.

Disappearance of texture [100] seems to connect with higher cold-hardened texture [111] and

starts to recrystallization, which expected that in high deformed states (after technological

annealing after 60%) disappearance of texture [100] would lead to decreasing of one in a two

peaks of microhardness.

Fig. 6. 3D photos of Mo-47%Re alloy with 0.5 mm thick. (a) as-rolled, (b) annealed at 1673

K, 1 h and (c) annealed at 1873 K, 1 h, respectively.

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Mo-47Re t=0.5ｍｍ as-rolled

100µm

RD

Fig. 6a 3D photos of as-rolled Mo-47%Re alloy with 0.5 mm thick.

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Mo-47Re t=0.5ｍｍ TA=1400℃

100µm

RD

Fig. 6b 3D photos of 0.5 mm thick Mo-47%Re alloy annealed at 1673 K, 1 h.

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Mo-47Re t=0.5ｍｍ TA=1600℃

100µm

RD

Fig. 6c 3D photos of 0.5 mm thick Mo-47%Re alloy annealed at 1873 K, 1 h.

Fig. 6. RD plane (gray color) : perpendicular plane to rolling direction = perpendicular plane

to RD

ND plane = Rolling plane : perpendicular plane to ND = (wide plane)

TD plane : perpendicular plane to TD direction (thickness / height)

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Fig. 7. Deformation band (blue) in rolled iron (red – rolling direction) by Kolja-san.

500 1000 1500 2000

200

250

300

350

400

450

500

550

600

650

Hv

Annealing temperature, K

1 mm 0.9 mm 0.8 mm 0.5 mm 0.27 mm

Fig. 8. Hardness (HV ; P=10kgf) as a function of annealing temperature (1 hr)

1 µµµµm

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200 400 600 800 1000 1200 1400

0

10

20

30

40

Elo

nga

tion,

%

Test temperature, K

Uniform elongation Total elongation

Fig. 9. Tensile properties of the as-rolled Mo-47%Re sheet with 1.0 mm thickness

Sigma phases in the matrix by TEM analysis

ND plane = Rolling plane : perpendicular plane to ND = (wide plane)

260 nm

Fig. 10. TEM microstructure in Mo-47%Re, t=1.0 mm<Mo-Re 1mm d0.jpg>

ppt size : specimen 4 : L=190 nm, W=150 nm, specimen 3 : L=400 nm, W=150 nm

Table 2. EDS analysis by TEM in Mo-47%Re, t=1.0 mm

200 400 600 800 1000 1200 1400

600

800

1000

1200

1400

1600

1800

2000

Str

ess,

M

Pa

Test temperature, K

Yeild stress Tensile stress

Mo-47%Re, t=1.0 mm

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Re (wt%) Mo (wt%)

Spectrum 1

Spectrum 2

Spectrum 3

Spectrum 4

I am sorry that I was missed measured values in the above Table.

Please ask Kolja whai is the correct values !!

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Fig. 11. TEM observation in RD plane in 0.27 mm thick sheet

Bright field

1 µm

Dark field

[111]

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Fig. 12. Diffraction pattern of second phase in Mo-47%Re alloy (indexing of spots has not

yet completed. If possible, please ask Kolja how to identify them).

0,5 µm

Mo sigma

1,1,-2 2

, 0

,-

2

1,0,-1 2,-1,-

1,-1,0

1,-1,0

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0.5 µm

Fig. 13. Fig. 11. TEM microstructure in Mo-47%Re, t=1.0 mm<Mo-Re 1mm d0.jpg>

Sigma phases in the matrix by TEM analysis

TD plane : perpendicular plane to TD direction (thickness / height)

220 nm

ppt size : L=95 nm, W=30 nm

Fig. 13a. Enlarged one of the last photo in Fig. 13.

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<<To making easier for checking these problems, I recommend you to anneal one sample at

1400 - 1600 degree C for half an hour or more. >>

Microstructure examination by TEM after annealing treatment is

not conducted yet. Therefore it is better to compare the

microstructural change in detail between as-rolled sheets and

annealed ones, I think.

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2-2. Mo-50 wt.% Re

Fig. 14. Bend properties of as-welded Mo-50 wt.% Re at 77 K.

200 µm

Fig. 15. Fracture surface of postweld annealed Mo-50 wt.% Re bend tested at 77 K, v= 10

mm/min.

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Fig. 16. XRD spectrum of Mo-50 wt.% Re postweld annealed at 1473 K for (a) 1 h, (b) 2 h..

Fig. 17. SEM microstructure of Mo-50 wt.% Re weld after 60 % deformed by warm rolling

and annealed at 1573 K for 1 h.

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Fig. 18. TEM microstructure of Mo-50 wt.% Re weld after 65 % deformed by warm rolling

and annealed at 1473 K for 1 h.

Attention!!

As-rolled Mo-50%Re welds were irradiated at HT by SM reactor

in RIAR.