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Characterisation of Microstructure in model ODS Alloys. Arup Dasgupta Physical Metallurgy Division Indira Gandhi Centre for Atomic Research Kalpakkam – 603102, INDIA.
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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
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
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)
Machining Mult. Pass CW Int. Heat Trtmt. Extr. Rods Mother Tubes Clad Tubes Processing Scheme Courtesy: IGCAR ODS Task force, ARCI - Hyderabad
Importance of Microstructural & Microchemical Investigations MA systems
Samples Studied #ODS 0: 48h Milled Fe-0.2Ti-0.35Y2O3 Powder #ODS 1: Fe-0.35Y2O3 Fe (150µm) and Y2O3 (1.33µm) ballmilled / 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) ballmilled / 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) attritormilled / 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
Samples Studied #ODS 0: 48h Milled Fe-0.2Ti-0.35Y2O3 Powder #ODS 1: Fe-0.35Y2O3 Fe (150µm) and Y2O3 (1.33µm) ballmilled / 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) ballmilled / 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) attritormilled / 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
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
Samples Studied #ODS 0: 48h Milled Fe-0.2Ti-0.35Y2O3 Powder #ODS 1: Fe-0.35Y2O3 Fe (150µm) and Y2O3 (1.33µm) ballmilled / 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) ballmilled / 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) attritormilled / 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
Samples Studied #ODS 0: 48h Milled Fe-0.2Ti-0.35Y2O3 Powder #ODS 1: Fe-0.35Y2O3 Fe (150µm) and Y2O3 (1.33µm) ballmilled / 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) ballmilled / 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) attritormilled / 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
Samples Studied #ODS 0: 48h Milled Fe-0.2Ti-0.35Y2O3 Powder #ODS 1: Fe-0.35Y2O3 Fe (150µm) and Y2O3 (1.33µm) ballmilled / 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) ballmilled / 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) attritormilled / 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
SADP Selection Rule FCC : (h k l) all odd / even BCC : h + k + l even
Samples Studied #ODS 0: 48h Milled Fe-0.2Ti-0.35Y2O3 Powder #ODS 1: Fe-0.35Y2O3 Fe (150µm) and Y2O3 (1.33µm) ballmilled / 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) ballmilled / 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) attritormilled / 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
Samples Studied #ODS 0: 48h Milled Fe-0.2Ti-0.35Y2O3 Powder #ODS 1: Fe-0.35Y2O3 Fe (150µm) and Y2O3 (1.33µm) ballmilled / 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) ballmilled / 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) attritormilled / 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
Samples Studied #ODS 0: 48h Milled Fe-0.2Ti-0.35Y2O3 Powder #ODS 1: Fe-0.35Y2O3 Fe (150µm) and Y2O3 (1.33µm) ballmilled / 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) ballmilled / 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) attritormilled / 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
Samples Studied #ODS 0: 48h Milled Fe-0.2Ti-0.35Y2O3 Powder #ODS 1: Fe-0.35Y2O3 Fe (150µm) and Y2O3 (1.33µm) ballmilled / 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) ballmilled / 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) attritormilled / 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
Pore Density ~0.3% aligned along Extrusion direction Tears
Y L : 0.63 % Ti K : 0.36 % Cr K : 8.95 % Fe K : 87.6 % W L : 2.44 %
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 a=10.6 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.