Handbook on the Properties of Niobium, Moybdenum, Tantalum, Tungsten and some of their Alloys

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CONTENTS

Page INTRODUCTION

ii

LIST OF ABBREVIATIONS

xx

CHAPTER I - NIOBIUM AND NIOBIUM ALLOYS 1. PHYSICAL PROPERTIES OF NIOBIUM METAL 1.1 Atomic Number 1.2 Crystal Structure 1.3 Density 1.4 Melting Point 1.5 Vapour Pressure 1.6 Specific Heat 1.7 Thermal Conductivity 1.8 Thermal Expansion 1.9 Electrical Resistivity 1.10 Absorption Cross-Section (Thermal Neutrons) 1.11 Spectral Emissivity 2. MECHANICAL PROPERTIES OF NIOBIUM METAL 2.1 Typical Analyses 2.2 Tensile Properties at High Temperature (Mean values) 2.3 Tensile Properties at Low Temperature Ductile-to-Brittle Transition 2.4 Hardness 2.5 Young's Modulus 2.6 Fatigue Strength 2.7 Creep Properties 2.7.1 Stress-Rupture Data 2.7.2 Creep Stress 2.8 Effect of Impurities (Oxygen and Nitrogen) 2.8.1 Effect on Properties at Room Temperature (Annealed metal) 2.8.2 Effect on Properties at High Temperatures (Annealed metal) , 2.8.3 Effect on Hardness at Room Temperature (Annealed metal) 2.9 Cold Working, Stress-Relief and Recrystallization 2.9.1 Cold Working 2.9.2 Stress-Relief 2.9.3 Recrystallization

iv

2 2 2

2 2 2 2 2 2

4 5

5 5 5

6 6 10 10 10 10 10 12 12

12 12 14 14 14 14 14

Page 3. CORROSION BY GASES, CHEMICALS AND LIQUID METALS 3.1 Resistance to Oxidation 3.2 Resistance to Water and Water Vapour 3.3 Resistance to Various Chemicals 3.4 Resistance to Liquid Metals

16 16

4. FABRICATION 4.1 Welding and Brazing 4.2 Forming 4.3 Machining

20 20 20

18 20 20

22

5. NIOBIUM ALLOYS - PURPOSE AND COMPOSITION 5.1 General 5.2 Solid Solution Strengthening 5.3 Dispersion Strengthening 5.4 Composition of Niobium Alloys

22 22

22 24 26

6. PHYSICAL PROPERTIES OF SOME ALLOYS

30

7. MECHANICAL PROPERTIES OF SOME ALLOYS 7.1 Tensile Properties at High Temperatures (Mean values) 7.2 Materials Advisory Board Targets 7.3 Creep Properties 7.3.1 Stress-Rupture 7.3.2 Creep Stress 7.4 Young's Modulus 7.5 Stress Relief and Recrystallization 7.6 Ductile-to-Brittle Transition Temperature

32

38 42 44 44

8. CORROSION OF ALLOYS BY GASES, CHEMICALS AND LIQUID METALS 8.1 Resistance to Oxidation. General 8.1.1 Resistance to Oxidation of Some Common Alloys 8.2 Resistance to Water and Water Vapour 8.3 Resistance to Chemicals 8.4 Resistance to Liquid Metals

48 48 52 52 52 52

9. FABRICATION 9.1 Welding

54 54

32 36 36 36

9.2

Brazing

56

9.3 9.4 9.5

Forming Machining Descaling

58

62 62

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Page CHAPTER II - TANTALUM AND TANTALUM ALLOYS 1. PHYSICAL PROPERTIES OF TANTALUM METAL 1.1 Atomic Number 1.2 Crystal Structure 1.3 Density 1.4 Melting Point 1.5 Vapour Pressure 1.6 Specific Heat 1.7 Thermal Conductivity 1.8 Thermal Expansion (Mean) 1.9 Electrical Resistivity 1.10 Absorption Cross-Section (Thermal Neutrons) 1.11 Spectral Emissivity

64 64 64 64 64 64 66 66

2. MECHANICAL PROPERTIES OF TANTALUM METAL 2.1 Typical Analyses 2.2 Tensile Properties at High Temperatures (Mean Values) 2.3 Tensile Properties at Low Temperatures - Ductile-toBrittle Transition 2.4 Hardness 2.5 Young's IYlodulus 2.6 Fatigue Strength 2.7 Creep Properties 2.7.1 Stress Rupture Data (Mean values) 2.7.2 Creep Stress 2.8 Effect of Impurities 2.9 Cold-Working - Stress-Relief - Recrystallization 2.9.1 Cold-Working 2.9.2 Stress-Relief 2.9.3 Recrystallization

68 68

66 66 68 68

70 70 72 72 72 74 74 74 74 76 76 76 76

3. CORROSION BY GASES, CHEMICALS AND LIQUID METALS 3.1 Resistance to Oxidation 3.2 Resistance to Various Chemicals 3.3 Effect of Hydrogen 3.4 Resistance to Liquid Metals

80 80 80

4. FABRICATION 4.1 Welding and Brazing

82 82

4.2

Forming and Machining

78 78

82

5. TANTALUM ALLOYS 5.1 General 5.2 Solid Solution Strengthening 5.3 Dispersion Strengthening 5.4 Composition of Some Alloys

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82 82 84

86 86

Page 6. PHYSICAL PROPERTIES OF SOME ALLOYS

90

7. MECHANICAL PROPERTIES OF SOME ALLOYS 7.1 Tensile Properties at High Temperatures (Mean values) 7.2 Materials Advisory Board Targets 7.3 Creep Properties 7.3.1 Stress Rupture Data 7.3.2 Creep Stress 7.4 Young's Modulus 7.5 Stress-Relief and Recrystallization 7.6 Ductile-to-Brittle Transition Temperature

90 90 92 94 94 94 96 96 96

S. CORROSION OF ALLOYS BY GASES, CHEMICALS AND LIQUID METALS S.l Resistance to Oxidation - General S.2 Resistance to Chemicals S.3 Resistance to Liquid Metals

9S 9S 100 100

9. FABRICATION

9.1 9.2 9.3 9.4 9.5

100 100 102 102 106 106

Welding Brazing Forming Machining Descaling

CHAPTER III - MOLYBDENUM AND MOLYBDENUM ALLOYS 1. PHYSICAL PROPERTIES OF MOLYBDENUM METAL 1.1 Atomic Number 1.2 Crystal Structure 1. 3 Densi ty 1.4 Melting Point 1.5 Vapour Pressure 1.6 Specific Heat 1.7 Thermal Conductivity 1.S Thermal Expansion 1.9

Electrical Resistivity

1.10 Absorption Cross-Section (Thermal Neutrons) 1.11 Spectral Emissivity 2. MECHANICAL PROPERTIES OF MOLYBDENUM METAL 2. 1 Typical Analyses 2.2 Tensile Properties at High Temperatures (Mean values) 2.3 Tensile Properties at Low Temperatures Ductile-Brittle Transition

x

lOS lOS lOS lOS 108

lOS lOS 110 110 110 110 110

112 112

112 114

Page 2.4 2.5 2.6 2.7

2.8 2.9

Hardness Young's Modulus (Mean values) Fatigue strength Creep Properties 2.7.1 stress-Rupture Data 2.7.2 Creep stress Effects of Impurities Cold-Working - stress-Relief - Recrystallization 2.9.1 Cold-Working 2.9.2 Stress-Relief 2.9.3 Recrystallization

3. CORROSION BY GASES, 3.1 Resistance to 3.2 Resistance to 3.3 Resistance to

CHEMICALS AND LIQUID METALS Oxidation Various Chemicals Liquid Metals

120 120 120 122 122 122 122 124 124 124 124 126 126 128 128

4. FABRICATION 4.1 Welding 4.2 Forming 4.3 Machining

128 128 130 130

5. MOLYBDENUM ALLOYS 5.1 General 5.1.1 Improvement of Resistance to Oxidation 5.1.2 Improvement of Recrystallization Temperature 5.1.3 Improvement of Mechanical Properties at High Temperature 5.1.3.1 Dispersion Strengthening 5.1.3.2 Solid Solution Strengthening 5.1.4 Improvement of Welding Properties

132 132 132 132 132 132 134 138

6. PHYSICAL PROPERTIES OF SOME ALLOYS 6.1 Composition of Principal Alloys 6.2 Physical Properties

138 138 140

7. MECHANICAL PROPERTIES OF SOME ALLOYS 7.1 Tensile Properties at High Temperatures (Mean values) 7.2 Materials Advisory Board Targets 7.3 Creep Properties 7.3.1 Stress-Rupture Data 7.3.2 Creep Stress 7.4 Young's Modulus 7.5 Stress-Relief and Recrystallization 7.6 Ductile-to-Brittle Transition Temperature

142

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142 144 146

146 148 150 150 152

Page 8. CORROSION BY GASES, CHEMICALS AND LIQUID METALS 8.1 Resistance to Oxidation 8.2 Resistance to Corrosion by Chemicals and Liquid IVietal

158 158

9. FABRICATION 9.1 Welding 9.2 Brazing 9.3 Forming 9.4 Machining

160 160 162 164 166

160

CHAPTER IV - TUNGSTEN AND TUNGSTEN ALLOYS 1. PHYSICAL PROPERTIES OF TUNGSTEN METAL 1.1 Atomic Number 1.2 Crystal Structure 1. 3 Densi ty 1.4 Melting Point 1.5 Vapour Pressure 1.6 Specific Heat 1.7 Thermal Conductivity 1.8 Thermal Expansion 1.9 Electrical Resistivity 1.10 Absorption Cross-Section (Thermal Neutrons) 1.11 Spectral Emissivity

168 168 168 168 168 168 168 168 170 170 170 170

2. MECHANICAL PROPERTIES OF TUNGSTEN METAL 2.1 Typical Analyses 2.2 Tensile Properties at High Temperatures (Mean values) 2.3 Ductile-to-Brittle Transition 2.4 Hardness 2.5 Young's Modulus 2.6 Fatigue Strength 2.7 Creep Properties 2.7.1 Stress Rupture Data 2.7.2 Creep Stress

170 170 172 174 176 178 178 178 178 178

2.8

Effect of Impurities

178

2.9

Cold-Working - Stress-Relief - Recrystallization 2.9.1 Cold-Working 2.9.2 Stress-Relief 2.9.3 Recrystallization

180 180 180 180

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Page 3. CORROSION BY GASES, 3.1 Resistance to 3.2 Resistance to 3.3 Resistance to 3.4 Compatibility

CHEMICALS AND LIQUID METALS Oxidation Chemicals Liquid Metals with Refractory Materials

182 182 182 182 184

4. FABRICATION 4.1 Welding 4.2 Forming 4.3 Machining

184 184 184 186

5. TUNGSTEN ALLOYS 5.1 General 5.2 Improvement of Mechanical Properties of Wrought Alloys at High Temperatures 5.2.1 Solid Solution Strengthening 5.2.2 Dispersion Strengthening 5.2.3 Combinations of Solid Solution and Dispersion Strengthening 5.3 Alloys Produced by Liquid Phase Sintering or Infiltration

186 186 186 186 190 192 194

PHYSICAL PROPERTIES OF ALLOYS 6.1 Composition of the Most Advanced Alloys 6.2 Physical Properties

194 194 196

7. MECHANICAL PROPERTIES 7.1 Tensile Properties at High Temperatures (Experimental values) 7.2 Materials Advisory Board Targets 7.3 Creep Properties 7.3.1 Stress Rupture 7.3.2 Creep Stress 7.4 Stress-Relief and Recrystallization 7.5 Ductile-to-Brittle Transition

196

6.

196 200 200 200 202 202 206

8.

CORROSION BY GASES AND CHEMICALS 8.1 Resistance to Oxidation 8.2 Corrosion by Chemicals

208 208 210

9.

FABRICATION 9.1 Welding 9.2 Brazing and Diffusion Bonding 9.3 Forming 9.4 Machining

210

10. COMPARISON OF THE TENSILE STRENGTH OF REFRACTORY METALS AND THEIR ALLOYS

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210 210 212 214

214

Page CHAPTER V - PROTECTIVE COATINGS 1. GENERAL 1.1 Essential Requirements for Protective Coatings 1.2 Brief Review of the Most Advanced Protective Coatings

220 220 224

2. PROTECTIVE COATINGS FOR NIOBIUM AND NIOBIUM ALLOYS 2.1 Types of Coating 2.1.1 Spray Metallisation 2.1.2 Hot-Dipping 2.1.3 Cementation and Diffusion 2.1.4 Metal Cladding 2.2 Performance of Coatings and Effect of Transition Temperature

224 224 226 228 232 238

3. PROTECTIVE COATINGS FOR TANTALUM AND TANTALUM ALLOYS 3.1 Types of Coating 3.1.1 Aluminides (General Telephone and Electronics) 3.1.2 Beryllides (General Telephone and Electronics) 3.1.3 Silicides 3.1.4 Metal + Ceramic

242 242 244 246 246 248

4. PROTECTIVE COATINGS FOR MOLYBDENUM AND MOLYBDENUM ALLOYS 4.1 Types of Coating 4.1.1 Silicides 4.1.2 Sprayed Metals or Alloys 4.1.3 Electroplating 4.1.3.1 Metals 4.1.3.2 Metals + Ceramics 4.1.4 Miscellaneous

250 250 252 260 262 262 262 262

5. PROTECTIVE COATINGS FOR TUNGSTEN AND TUNGSTEN ALLOYS 5.1 Types of Coating 5.1.1 Silicides 5.1.2 Metals 5.1.3 Ceramics 5.2 Miscellaneous

264 264 266 268 270 270

6. SUMMARY OF PERFORMANCE OF COATED REFRACTORY METALS 6.1 Summary of Mean Performances 6.2 Current Maximum Performances

272 272 272

SELECTED BIBLIOGRAPHY

277

DISTRIBUTION

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