Characterisation of Microstructure in model ODS Alloys

1
Characterisation of Microstructure in model ODS
Alloys

• Arup Dasgupta
• Physical Metallurgy DivisionIndira Gandhi Centre
  for Atomic Research
• Kalpakkam 603102, INDIA

A collaborative work between IGCAR, Kalpakkam and
International Advanced Research Centre for Powder
Metallurgy and New Materials, Hyderabad
2
SCHEME

• The Issue
• What kind of alloy is under development
• Processing Scheme
• Importance of microstructure and microchemistry
  investigations in alloy development
• This Talk
• Types of samples studies so far
• Results and Discussion
• Summary

3
The Alloy under development

• 9Cr-0.12C-2W-0.2Ti-0.35Y2O3 Ferritic/Martensitic
  steel chosen
• because of advantages over austenitic stainless
  steels
• Higher thermal conductivity
• Lower thermal expansion
• Lower void swelling during irradiation
• Excellent high temperature creep resistance
• W ? Mo replacement for solid solution
  strengthening reduced activation
• Ti ? Helps to get finer dispersoids
• Mandate Clad Tubes (6.6mm OD, 0.45mm thick, 2.65
  m long)

4
Processing Scheme
Courtesy IGCAR ODS Task force, ARCI - Hyderabad
5
Importance of Microstructural Microchemical
Investigations MA systems
6
Samples Studied

• ODS 0 48h Milled Fe-0.2Ti-0.35Y2O3 Powder
• ODS 1 Fe-0.35Y2O3
• Fe (150µm) and Y2O3 (1.33µm) ball milled / 30h,
  annealed at 973K / vacuum , double compacted,
  double sintered at 1323K / H2
• ODS 2 Fe-0.2Ti-0.35Y2O3
• Fe (150µm), Ti (105µm) and Y2O3 (1.33µm) ball
  milled / 30h, annealed at 973K / vac., double
  compacted, double sintered at 1323K / H2
• ODS 3 Fe-0.2Ti-0.35Y2O3 - Forged
• Fe (150µm), Ti (105µm) and Y2O3 (10-20nm)
  attritor milled / 20h, degassed at 723K sealed.
  Can hipped/ forged at 1323K/ 1000MPa
• ODS 4 Fe-0.12C-9Cr-2W-0.2Ti Pre-alloyed
  Powder SEM Only
• ODS 5 Yttria Powder
• ODS 6 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Milled
  Powder
• ODS 7 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Extruded
  at 1050oC
• B1-ODS-S150-Z04-C46-D04-E1050-ER09

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Samples Studied

• ODS 0 48h Milled Fe-0.2Ti-0.35Y2O3 Powder
• ODS 1 Fe-0.35Y2O3
• Fe (150µm) and Y2O3 (1.33µm) ball milled / 30h,
  annealed at 973K / vacuum , double compacted,
  double sintered at 1323K / H2
• ODS 2 Fe-0.2Ti-0.35Y2O3
• Fe (150µm), Ti (105µm) and Y2O3 (1.33µm) ball
  milled / 30h, annealed at 973K / vac., double
  compacted, double sintered at 1323K / H2
• ODS 3 Fe-0.2Ti-0.35Y2O3 - Forged
• Fe (150µm), Ti (105µm) and Y2O3 (10-20nm)
  attritor milled / 20h, degassed at 723K sealed.
  Can hipped/ forged at 1323K/ 1000MPa
• ODS 4 Fe-0.12C-9Cr-2W-0.2Ti Pre-alloyed
  Powder SEM Only
• ODS 5 Yttria Powder
• ODS 6 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Milled
  Powder
• ODS 7 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Extruded
  at 1050oC
• B1-ODS-S150-Z04-C46-D04-E1050-ER09

8

9

• 3 size ranges
• large, facetted (Fe-Co)
• 50 75 nm (Fe-Ti)
• sub-10 nm (Fe)

Co
Fe
Courtesy Institute  Nano-science Initiative
IISc, Bangalore - Tecnai F-30

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Samples Studied

• ODS 0 48h Milled Fe-0.2Ti-0.35Y2O3 Powder
• ODS 1 Fe-0.35Y2O3
• Fe (150µm) and Y2O3 (1.33µm) ball milled / 30h,
  annealed at 973K / vacuum , double compacted,
  double sintered at 1323K / H2
• ODS 2 Fe-0.2Ti-0.35Y2O3
• Fe (150µm), Ti (105µm) and Y2O3 (1.33µm) ball
  milled / 30h, annealed at 973K / vac., double
  compacted, double sintered at 1323K / H2
• ODS 3 Fe-0.2Ti-0.35Y2O3 - Forged
• Fe (150µm), Ti (105µm) and Y2O3 (10-20nm)
  attritor milled / 20h, degassed at 723K sealed.
  Can hipped/ forged at 1323K/ 1000MPa
• ODS 4 Fe-0.12C-9Cr-2W-0.2Ti Pre-alloyed
  Powder SEM Only
• ODS 5 Yttria Powder
• ODS 6 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Milled
  Powder
• ODS 7 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Extruded
  at 1050oC
• B1-ODS-S150-Z04-C46-D04-E1050-ER09

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Porosity 14
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Samples Studied

• ODS 0 48h Milled Fe-0.2Ti-0.35Y2O3 Powder
• ODS 1 Fe-0.35Y2O3
• Fe (150µm) and Y2O3 (1.33µm) ball milled / 30h,
  annealed at 973K / vacuum , double compacted,
  double sintered at 1323K / H2
• ODS 2 Fe-0.2Ti-0.35Y2O3
• Fe (150µm), Ti (105µm) and Y2O3 (1.33µm) ball
  milled / 30h, annealed at 973K / vac., double
  compacted, double sintered at 1323K / H2
• ODS 3 Fe-0.2Ti-0.35Y2O3 - Forged
• Fe (150µm), Ti (105µm) and Y2O3 (10-20nm)
  attritor milled / 20h, degassed at 723K sealed.
  Can hipped/ forged at 1323K/ 1000MPa
• ODS 4 Fe-0.12C-9Cr-2W-0.2Ti Pre-alloyed
  Powder SEM Only
• ODS 5 Yttria Powder
• ODS 6 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Milled
  Powder
• ODS 7 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Extruded
  at 1050oC
• B1-ODS-S150-Z04-C46-D04-E1050-ER09

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Porosity 20
14
Samples Studied

• ODS 0 48h Milled Fe-0.2Ti-0.35Y2O3 Powder
• ODS 1 Fe-0.35Y2O3
• Fe (150µm) and Y2O3 (1.33µm) ball milled / 30h,
  annealed at 973K / vacuum , double compacted,
  double sintered at 1323K / H2
• ODS 2 Fe-0.2Ti-0.35Y2O3
• Fe (150µm), Ti (105µm) and Y2O3 (1.33µm) ball
  milled / 30h, annealed at 973K / vac., double
  compacted, double sintered at 1323K / H2
• ODS 3 Fe-0.2Ti-0.35Y2O3 - Forged
• Fe (150µm), Ti (105µm) and Y2O3 (10-20nm)
  attritor milled / 20h, degassed at 723K sealed.
  Can hipped/ forged at 1323K/ 1000MPa
• ODS 4 Fe-0.12C-9Cr-2W-0.2Ti Pre-alloyed
  Powder SEM Only
• ODS 5 Yttria Powder
• ODS 6 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Milled
  Powder
• ODS 7 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Extruded
  at 1050oC
• B1-ODS-S150-Z04-C46-D04-E1050-ER09

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Porosity 1
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SADP
Selection Rule FCC (h k l) all odd / even BCC
h k l even
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DF
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IMPURITY
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Samples Studied

• ODS 0 48h Milled Fe-0.2Ti-0.35Y2O3 Powder
• ODS 1 Fe-0.35Y2O3
• Fe (150µm) and Y2O3 (1.33µm) ball milled / 30h,
  annealed at 973K / vacuum , double compacted,
  double sintered at 1323K / H2
• ODS 2 Fe-0.2Ti-0.35Y2O3
• Fe (150µm), Ti (105µm) and Y2O3 (1.33µm) ball
  milled / 30h, annealed at 973K / vac., double
  compacted, double sintered at 1323K / H2
• ODS 3 Fe-0.2Ti-0.35Y2O3 - Forged
• Fe (150µm), Ti (105µm) and Y2O3 (10-20nm)
  attritor milled / 20h, degassed at 723K sealed.
  Can hipped/ forged at 1323K/ 1000MPa
• ODS 4 Fe-0.12C-9Cr-2W-0.2Ti Pre-alloyed
  Powder SEM Only
• ODS 5 Yttria Powder
• ODS 6 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Milled
  Powder
• ODS 7 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Extruded
  at 1050oC
• B1-ODS-S150-Z04-C46-D04-E1050-ER09

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Samples Studied

• ODS 0 48h Milled Fe-0.2Ti-0.35Y2O3 Powder
• ODS 1 Fe-0.35Y2O3
• Fe (150µm) and Y2O3 (1.33µm) ball milled / 30h,
  annealed at 973K / vacuum , double compacted,
  double sintered at 1323K / H2
• ODS 2 Fe-0.2Ti-0.35Y2O3
• Fe (150µm), Ti (105µm) and Y2O3 (1.33µm) ball
  milled / 30h, annealed at 973K / vac., double
  compacted, double sintered at 1323K / H2
• ODS 3 Fe-0.2Ti-0.35Y2O3 - Forged
• Fe (150µm), Ti (105µm) and Y2O3 (10-20nm)
  attritor milled / 20h, degassed at 723K sealed.
  Can hipped/ forged at 1323K/ 1000MPa
• ODS 4 Fe-9Cr-2W-0.2Ti Pre-alloyed Powder
  SEM Only
• ODS 5 Yttria Powder
• ODS 6 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.16C Milled
  Powder
• ODS 7 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.16C Extruded
  at 1050oC
• B1-ODS-S150-Z04-C46-D04-E1050-ER09

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Av. Particle Size (XRD) 42 nm
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Samples Studied

• ODS 0 48h Milled Fe-0.2Ti-0.35Y2O3 Powder
• ODS 1 Fe-0.35Y2O3
• Fe (150µm) and Y2O3 (1.33µm) ball milled / 30h,
  annealed at 973K / vacuum , double compacted,
  double sintered at 1323K / H2
• ODS 2 Fe-0.2Ti-0.35Y2O3
• Fe (150µm), Ti (105µm) and Y2O3 (1.33µm) ball
  milled / 30h, annealed at 973K / vac., double
  compacted, double sintered at 1323K / H2
• ODS 3 Fe-0.2Ti-0.35Y2O3 - Forged
• Fe (150µm), Ti (105µm) and Y2O3 (10-20nm)
  attritor milled / 20h, degassed at 723K sealed.
  Can hipped/ forged at 1323K/ 1000MPa
• ODS 4 Fe-0.12C-9Cr-2W-0.2Ti Pre-alloyed
  Powder SEM Only
• ODS 5 Yttria Powder
• ODS 6 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Milled
  Powder
• ODS 7 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Extruded
  at 1050oC
• B1-ODS-S150-Z04-C46-D04-E1050-ER09

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(No Transcript)
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Samples Studied

• ODS 0 48h Milled Fe-0.2Ti-0.35Y2O3 Powder
• ODS 1 Fe-0.35Y2O3
• Fe (150µm) and Y2O3 (1.33µm) ball milled / 30h,
  annealed at 973K / vacuum , double compacted,
  double sintered at 1323K / H2
• ODS 2 Fe-0.2Ti-0.35Y2O3
• Fe (150µm), Ti (105µm) and Y2O3 (1.33µm) ball
  milled / 30h, annealed at 973K / vac., double
  compacted, double sintered at 1323K / H2
• ODS 3 Fe-0.2Ti-0.35Y2O3 - Forged
• Fe (150µm), Ti (105µm) and Y2O3 (10-20nm)
  attritor milled / 20h, degassed at 723K sealed.
  Can hipped/ forged at 1323K/ 1000MPa
• ODS 4 Fe-0.12C-9Cr-2W-0.2Ti Pre-alloyed
  Powder SEM Only
• ODS 5 Yttria Powder
• ODS 6 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Milled
  Powder
• ODS 7 Fe-9Cr-2W-0.2Ti-0.35Y2O3-0.12C Extruded
  at 1050oC
• B1-ODS-S150-Z04-C46-D04-E1050-ER09

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Pore Density 0.3 aligned along Extrusion
direction ? Tears
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Y L 0.63 Ti K 0.36 Cr K 8.95 Fe K
87.6 W L 2.44
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0
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Summary

• Seven sets of model materials studied (powders,
  milled, compacted products)
• Higher Milling Duration ? Agglomeration
• The sintered products were porous, 14-20 but
  forged material had a porosity 1. Extruded
  material had porosity 0.3 only!
• Yttria ? bcc with a10.6 Å
• Forged sample ? fine bcc yttria particles with an
  av. size 10-20 nm some were 5-7 nm and some
  were agglomerated there appeared to be an
  orientation between the Yttria and the
  rextallised ferrite grains
• Prealloyed powder yttria powder ? desired sizes
  quite pure
• The extruded ODS steel ? desired composition,
  fine martensite laths (100 nm wide) within the
  elongated grains, very fine ( 3nm) yttria.

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Contributors