Handbook Properties and Selection Nonferrous Alloys and Spl Purpose Mtls (1992) WW Part 14 doc

Resistance to specific according agents. Lutetium does not react with cold or hot water, but it reacts vigorously with dilute acids. Concentrated sulfuric acid slowly attacks lutetium. The presence of the fluoride ion retards acid attack due to the formation of LuF 3 on the surface of the metal. Mechanical Properties Tensile properties. About the same as those of erbium Hardness. 44 HV Poisson's ratio. 0.261 Elastic modulus. At 27 °C: tension, 68.6 GPa; shear, 27.2 GPa; bulk, 47.6 GPa Elastic constants along crystal axes. At 27 °C: c 11 = 86.23 GPa; c 12 = 32.0 GPa; c 13 = 28.0 GPa; c 33 = 80.86 GPa; c 44 = 26.79 GPa Liquid surface tension. 0.940 N/m at 1665 °C Mischmetal (MM) Compiled by K.A. Gschneidner, Jr. and B.J. Beaudry, Ames Laboratory, U.S. Department of Energy, Iowa State University Mischmetal is used as an alloying additive in ferrous alloys to scavenge sulfur, oxygen, and other substances. Mischmetal is also added to magnesium-base alloys to improve high-temperature strength and to ductile irons to nodularize graphite. It is used as a reductant to produce the volatile rare earth metals (samarium, europium, and ytterbium) from their oxides. Other uses of mischmetal include lighter flints, galvanizing alloys, and mischmetal cobalt (cerium-free mischmetal-nickel alloys are used as hydrogen storage alloys), and permanent magnets. Mischmetal oxidizes at room temperature in air. Turnings can be ignited easily and burn white hot. Finely divided mischmetal should not be handled in air. Because mischmetal is an indefinite mixture of rare earth metals, the properties of a particular mischmetal depend on its composition, which in turn depends on the mineral source for the mixture. Listed below are the properties of two of the most common high-purity mischmetal mixtures. Because most commercial mischmetals contain several atomic percent of iron and magnesium (about 1 wt%), their properties may differ somewhat from those listed below. Many values are estimated and are marked as such. Bastnasite-Derived Mischmetal Specifications UNS number. E21000 Chemical Composition Composition limits. Total mixed rare earths: 99.0 min; mixture consists of 39 La, 38 Ce, 16 Nd, 6 Pr, 1 other rare earth Structure Crystal structure. α phase, double close-packed hexagonal, P6 3 /mmc 6h 4 D ; a = 0.3718 nm, c = 1.1978 nm at 24 °C. β phase, body-centered cubic Minimum interatomic distance. At 24 °C: r a = 0.1859 nm; r c = 0.1842 nm; radius CN 12 = 0.1851 Mass Characteristics Atomic weight. 140.1 Density. 6.490 g/cm 3 at 24 °C; Volume change on freezing. 0.1% expansion (estimated) Thermal Properties Melting point. Melts over a range of temperatures from 888 to 895 °C Boiling point. Expected to evaporate incongruently with the initial loss of a major constituent (neodymium) by boiling at ~3100 °C Phase transformation temperature. α to β phase, 801 °C Coefficient of thermal expansion. At 24 °C. Linear: 8.7 μm/m · K. Volumetric: 26 × 10 -6 per K (both estimated) Specific heat. 0.193 kJ/kg · K at 25 °C Entropy. 467 J/kg · K at 25 °C (estimated) Latent heat of fusion. 47 kJ/kg Latent heat of transformation. 22 kJ/mol (estimated) Latent heat of combustion. For hexagonal R 2 O 3 at 25 °C: c H ∆ o = -6.4 MJ/kg MM (estimated); f G ∆ o = -6.0 MJ/kg MM (estimated) Recrystallization temperature. ~350 °C (estimated) Thermal conductivity. 13 W/m · K at 25 °C (estimated) Electrical Properties Electrical resistivity. Solid: 800 nΩ · m at 25 °C (estimated). Liquid: 1300 nΩ · m at 900 °C (estimated) Magnetic Properties Magnetic susceptibility. Volume, 1.6 × 10 -3 mks at 25 °C (estimated) Optical Properties Color. Metallic silver Spectral hemispherical emittance. Liquid, 30% (estimated) Chemical Properties General corrosion behavior. Commercial mischmetal is stable in air at room temperature due to presence of magnesium. Vacuum-melted mischmetal oxidizes in air at room temperature. Oxidation rates increase with increasing temperature and humidity. Resistance to specific corroding agents. Mischmetal reacts vigorously with dilute acids. The presence of the fluoride ion retards acid attack by the formation of rare earth fluoride (RF 3 ) on the surface of the metal. Mechanical Properties Tensile properties. At 24 °C: tensile strength, 138 MPa; yield strength, 48 MPa; elongation, 25%; reduction in area, 50% (all estimated) Hardness. 27 DPH Poisson's ratio. 0.27 (estimated) Elastic modulus. At 27 °C: tension, 35 GPa; shear, 14 GPa; bulk, 25 GPa (all estimated) Kinematic liquid viscosity. 0.46 mm 2 /s at 900 °C (estimated) Liquid surface tension. 0.70 N/m at 900 °C (estimated) Monazite-Derived Mischmetal Specifications UNS number. E31000 Chemical Composition Composition limits. Total mixed rare earths, 99.0 min; mixture consists of 50 Ce, 20 La, 20 Nd, 6 Pr, 2 Gd, 1.6 Y, <1 other rare earths Structure Crystal structure. α phase, double close-packed hexagonal, P6 3 /mmc 4 6h D ; a = 0.3695 nm; c = 1.1900 nm at 24 °C. β phase, probably body-centered cubic; a = 0.415 nm (estimated) Minimum interatomic distance. At 24 °C: r a = 0.1848 nm; r c = 0.1830 nm; radius CN 12 = 0.1839 nm Mass Characteristics Atomic weight. 140.1 Density. 6.612 g/cm 3 at 24 °C Volume change on freezing. 0.1% expansion (estimated) Thermal Properties Melting point. Melts over a range of temperatures from 899 to 913 °C Boiling point. Expected to evaporate incongruently with the initial loss of a major constituent (neodymium) by boiling at ~3100 °C Phase transformation temperature. α to β phase, 782 °C Coefficient of thermal expansion. At 24 °C. Linear: 8.6 μm/m · K. Volumetric: 26 × 10 -6 per K (both estimated) Specific heat. 0.195 kJ/kg · K at 25 °C (estimated) Entropy. At 298.15 K, 477 J/kg · K (estimated) Latent heat of fusion. 46 kJ/kg (estimated) Latent heat of transformation. 22 kJ/kg (estimated) Latent heat of combustion. For hexagonal R 2 O 3 at 25 °C: c H ∆ o = -6.4 MJ/kg MM (estimated); f G ∆ o = -6.0 MJ/kg MM (estimated) Recrystallization temperature. ~350 °C (estimated) Thermal conductivity. 13 W/m · K at 25 °C (estimated) Electrical Properties Electrical resistivity. Solid, 800 nΩ · m at 25 °C (estimated); liquid, 1300 nΩ · m at 925 °C (estimated) Magnetic Properties Magnetic susceptibility. Volume: 5.2 × 10 -3 mks at 25 °C (estimated) Optical Properties Color. Metallic silver Spectral hemispherical emittance. Liquid, 30% (estimated) Chemical Properties General corrosion behavior. Commercial mischmetal is stable in air at room temperature due to the presence of magnesium. Vacuum-melted mischmetal oxidizes in air at room temperature. Oxidation rates increase with increasing temperature and humidity. Resistance to specific corroding agents. Mischmetal reacts vigorously with dilute acids. The presence of the fluoride ion retards acid attack by the formation of rare earth fluoride (RF 3 ) on the surface of the metal. Mechanical Properties Tensile properties. At 24 °C: tensile strength, 138 MPa; yield strength, 48 MPa; elongation, 25%; reduction in area, 50% (all estimated) Hardness. 28 HV Poisson's ratio. 0.27 (estimated) Elastic modulus. At 27 °C: tension, 37 GPa; shear, 15 GPa; bulk, 27 GPa (all estimated) Kinematic liquid viscosity. 0.47 mm 2 /s at 920 °C (estimated) Liquid surface tension. 0.71 N/m at 920 °C (estimated) Neodymium (Nd) Compiled by K.A. Gschneidner, Jr. and B.J. Beaudry, Ames Laboratory, U.S. Department of Energy, Iowa State University The major use of neodymium is in high-strength Nd-Fe-B permanent magnets, which are the strongest magnets known. Neodymium, as a component (~20%) of mischmetal, is used as an alloying additive in ferrous alloys to scavenge sulfur, oxygen, and other elements, and to strengthen magnesium alloys. It is also used as a laser material and glass-coloring agent, and in petroleum cracking catalysts, carbon arc lights, lighter flints, and ceramic capacitors. Neodymium oxidizes at room temperature in air. It should be stored in a vacuum or inert atmosphere; storage in oil is not recommended. Turnings can be ignited easily and will burn white hot. Finely divided neodymium should not be handled in air. Structure Crystal structure. α phase, double close-packed hexagonal, P6 3 /mmc 6h 4 D ; a = 0.36582 nm, c = 1.17966 nm at 24 °C. β phase, body-centered cubic, Im3m 9 h O ; a = 0.413 nm at 883 °C Minimum interatomic distance. At 24 °C: r a = 0.18291 nm; r c = 0.18137 nm; radius CN 12 = 0.18214 nm Mass Characteristics Atomic weight. 144.24 Density. α phase, 7.008 g/cm 3 at 24 °C; β phase, 6.80 g/cm 3 at 883 °C; liquid, 6.72 g/cm 3 at 1025 °C; Volume change on freezing. 0.9% contraction Volume change on phase transformation. α to β phase, 0.1% volume expansion on heating Thermal Properties Melting point. 1021 °C Boiling point. 3074 °C Phase transformation temperature. α to β phase, 863 °C Coefficient of thermal expansion. At 24 °C. Linear: 9.6 μm/m · K. Linear along crystal axes: 7.6 μm/m · K along a axis, 13.5 μm/m · K along c axis. Volumetric: 28.7 × 10 -6 per K Specific heat. 0.1900 kJ/kg · K at 25 °C Entropy. At 25 °C: 492.9 J/kg · K Latent heat of fusion. 49.5 kJ/kg Latent heat of transformation. 21.0 kJ/kg Latent heat of vaporization. 2.271 MJ/kg at 25 °C Thermal conductivity. 16.5 W/m · K at 25 °C Heat of combustion. Hexagonal Nd 2 O 3 at 25 °C: c H ∆ o = -6.27 MJ/kg Nd; f G ∆ o = -5.96 MJ/kg Nd Recrystallization temperature. 400 °C Vapor pressure. 0.001 Pa at 955 °C; 0.101 Pa at 1175 °C; 10.1 Pa at 1500 °C; 1013 Pa at 2029 °C Electrical Properties Electrical resistivity. 643 nΩ · m at 25 °C; 68 nΩ · m at 4K. Liquid: 1510 nΩ · m at 1022 °C Ionization potential. Nd(I), 5.499 eV; Nd(II), 10.73, eV; Nd(III), 22.1 eV; Nd(IV), 40.41 eV Hall coefficient. +0.0971 nV · m/A · T at 25 °C Temperature of superconductivity. Bulk neodymium is not superconducting down to 0.25 K atmospheric pressure. Magnetic Properties Magnetic susceptibility. Volume: 3.62 × 10 -3 mks at 25 °C; obeys Curie-Weiss law above 35 K with an effective moment of 3.45 μ B , θ a = 5 K and θ c = 0 K Saturation magnetization. >35T at 2 K along <11 2 0> Magnetic transformation temperature. Néel temperatures at 7.5 K (cubic sites) and 19.9 K (hexagonal sites) Optical Properties Color. Metallic silver Spectral hemispherical emittance. 39.4% for λ= 645 nm from 1021 to 1567 °C Nuclear Properties Thermal neutron cross section. 48 b Chemical Properties General corrosion behavior. Neodymium oxidizes in air at room temperature, but at a slower rate than lanthanum or cerium. Oxidation rates increase with increasing temperature and humidity; interstitial impurities increase the rate of oxidation. Hydrogen will react with neodymium at room temperature. Resistance to specific corroding agents. Neodymium reacts vigorously with dilute acids and slowly with concentrated sulfuric acid. The presence of the fluoride ion retards acid attack due to the formation of NdF 3 on the surface of the metal. Mechanical Properties Tensile properties. Tensile strength, 164 MPa; yield strength, 71 MPa; elongation, 25%; reduction in area, 72% Hardness. 18 HV Poisson's ratio. 0.281 Strain-hardening exponent. 0.28 Elastic modulus. At 27 °C: tension, 41.4 GPa; shear, 16.3 GPa; bulk, 31.8 GPa Elastic constants along crystal axes. At 27 °C: c 11 = 54.77 GPa; c 12 = 24.60 GPa; c 13 = 16.56 GPa; c 33 = 60.80 GPa; c 44 = 15.01 GPa Liquid surface tension. 0.687 N/m at 1021 °C Praseodymium (Pr) Compiled by K.A. Gschneidner, Jr. and B.J. Beaudry, Ames Laboratory, U.S. Department of Energy, Iowa State University Praseodymium, as a component (~5%) of mischmetal, is used as an alloying additive to ferrous alloys to scavenge impurities such as sulfur and oxygen, and to strengthen magnesium. It is also used as a glass-and ceramic-coloring agent, and in petroleum cracking-coloring catalysts, carbon arc lights, and PrCo 5 permanent magnets. PrNi 5 is used in adiabatic demagnetization refrigerators to attain ultralow temperatures (<1 mK). Praseodymium oxidizes at room temperature in air. It should be stored in vacuum or inert atmosphere; storage in oil is not recommended. Turnings can be ignited easily and will burn white hot. Finely divided praseodymium should not be handled in air. Structure Crystal structure. α phase, double close-packed hexagonal, P6 3 /mmc 6h 4 D ; a = 0.36721 nm, c = 1.18326 nm at 24 °C. β phase, body-centered cubic, Im3m 9 h O ; a = 0.1413 nm at 821 °C Minimum interatomic distance. At 24 °C: r a = 0.18360 nm; r c = 0.18197 nm; radius CN 12 = 0.18279 nm Mass Characteristics Atomic weight. 140.90765 Density. α phase, 6.773 g/cm 3 at 24 °C; β phase, 6.64 g/cm 3 at 821 °C; liquid, 6.59 g/cm 3 at 935 °C Volume change on freezing. 0.02% contraction Volume change on phase transformation. α to β phase, 0.5% volume expansion on heating Thermal Properties Melting point. 931 °C Boiling point. 3520 °C Phase transformation temperature. α to β phase, 795 °C Coefficient of thermal expansion. α phase at 24 °C. Linear: 6.7 μm/m · K. Linear along crystal axes: 4.5 μm/m · K along a axis, 11.2 μm/m · K along c axis. Volumetric: 20.2 × 10 -6 per K Specific heat. 0.1946 kJ/kg · K at 25 °C Entropy. At 25 °C, 524.5 J/kg · K Latent heat of fusion. 48.9 kJ/kg Latent heat of transformation. 22.5 kJ/kg Latent heat of vaporization. 2.524 MJ/kg at 25 °C Heat of combustion. For cubic Pr 6 O 11 at 25 °C: c H ∆ o = -6.73 MJ/kg Pr; f G ∆ o = -6.34 MJ/kg Pr Recrystallization temperature. About 400 °C Thermal conductivity. 12.5 W/m · K at 25 °C Vapor pressure. 0.001 Pa at 1083 °C; 0.101 Pa at 1333 °C; 10.1 Pa at 1701 °C; 1013 Pa at 2305 °C Electrical Properties Electrical resistivity. 700 nΩ · m at 25 °C; 22 nΩ · m at 4 K. Liquid: 1390 nΩ · m at 932 °C Ionization potential. Pr(I), 5.422 eV; Pr(II), 10.55 eV; Pr(III), 21.624 eV; Pr(IV), 38.98 eV; Pr(V), 57.45 eV Hall coefficient. +0.0709 nV · m/A · T at 25 °C Temperature of superconductivity. Bulk praseodymium is not superconducting down to 0.25 K at atmospheric pressure. Magnetic Properties Magnetic susceptibility. Volume: 3.34 × 10-3 mks at 25 °C; obeys Curie-Weiss law above 100 K with an effective moment of 3.56 μ B and θ 0 K Saturation magnetization. >35 T at 4 K along <11 2 0> Magnetic transformation temperature. Single-crystal strain-free praseodymium does not order magnetically; most polycrystalline samples order at various temperatures below 25 K. Optical Properties Color. Metallic silver Spectral hemispherical emittance. 28.4% for λ= 645 nm from 931 to 1537 °C Nuclear Properties Thermal neutron cross section. 11 b Chemical Properties Corrosion behavior. Praseodymium oxidizes in air at room temperature, but at a lower rate than lanthanum or cerium. Oxidation rates increase with temperature and humidity. Interstitial impurities in the metal increase the rate of corrosion in air. Hydrogen will react with praseodymium at room temperature. Resistance to specify corroding agents. Praseodymium reacts vigorously with dilute acids. It reacts slowly with concentrated sulfuric acid. The presence of the fluoride ion retards acid attack due to the formation of PrF 3 on the surface of the metal. Mechanical Properties Tensile properties. At 24 °C: tensile strength, 147 MPa; yield strength, 73 MPa; elongation, 15.4%; reduction in area, 67% Hardness. 20 HV Poisson's ratio. 0.281 Elastic modulus. At 27 °C: tension, 37.3 GPa; shear, 14.8 GPa; bulk, 28.8 GPa Elastic constants along crystal axes. At 27 °C: c 11 = 49.35 GPa; c 12 = 22.95 GPa; c 13 = 14.3 GPa; c 33 = 57.40 GPa; c 44 = 13.59 GPa Kinematic liquid viscosity. 0.432 mm 2 /s at 935 °C Liquid surface tension. 0.707 N/m at 935 °C Promethium (Pm) Compiled by K.A. Gschneidner, Jr. and B.J. Beaudry, Ames Laboratory, U.S. Department of Energy, Iowa State University Promethium is used in luminous watch dials and as a lightly shielded radioisotope power source. It is also a highly radioactive β emitter ( 147 Pm). Structure Crystal structure. α phase, double close-packed hexagonal, P6 3 /mmc 6h 4 D ; a = 0.365 nm, c = 1.165 at 24 °C. β phase, probably body-centered cubic, a = 0.410 nm (estimated) at 890 °C Minimum interatomic distance. At 24 °C: r a = 0.1825 nm; r c = 0.1797 nm; radius CN 12 = 0.1811 Mass Characteristics Atomic weight. 145 Density. α phase, 7.264 g/cm 3 at 24 °C; β phase, 6.99 g/cm 3 (estimated) at 890 °C; liquid, 6.9 g/cm 3 (estimated) at 1050 °C Thermal Properties Melting point. 1042 °C Boiling point. 3000 °C (estimated) Phase transformation temperature. 890 °C Coefficient of thermal expansion. At 24 °C. Linear (estimated): 11 μm/m · K. Linear along crystal axes 9 μm/m · K along a axis, 16 μm/m · K along c axis. Volumetric: 34 × 10 -6 per K Specific heat. 0.188 kJ/kg · K at 25 °C (estimated) Entropy. At 25 °C: 494 J/kg · K (estimated) Latent heat of fusion. 53 kJ/kg (estimated) Latent heat of transformation. 21 kJ/kg (estimated) Latent heat of vaporization. 2.4 MJ/kg at 25 °C (estimated) Thermal conductivity. 15 W/m · K at 27 °C (estimated) Heat of combustion. For monoclinic Pm 2 O 3 at 25 °C: c H ∆ o = -6.3 MJ/kg Pr; f G ∆ o = -6.0 MJ/kg Pm (estimated) Recrystallization temperature. 400 °C (estimated) Electrical Properties Electrical resistivity. 750 nΩ · m at 25 °C (estimated) Ionization potential. Pm(I), 5.554 eV; Pm(II), 10.90 eV; Pm(III), 22.3 eV; Pm(IV), 41.1 eV Magnetic Properties Magnetic susceptibility. Probably strongly paramagnetic with a susceptibility somewhat greater than that of cerium at 24 °C Magnetic transformation temperature. Probably exhibits two Néel temperatures that fall between those observed in neodymium and samarium Optical Properties Color. Metallic silver Chemical Properties General corrosion behavior. About the same as that of neodymium Resistance to specific corroding agents. About the same as that of neodymium Mechanical Properties Tensile properties. About the same as that of neodymium Hardness. 63 HK Poisson's ratio. 0.28 (estimated) Elastic modulus. At 27 °C: tension, 46 GPa (estimated); shear, 18 GPa; bulk, 33 GPa Liquid surface tension. 0.68 N/m (estimated) at 1045 °C Samarium (Sm) Compiled by K.A. Gschneidner, Jr. and B.J. Beaudry, Ames Laboratory, U.S. Department of Energy, Iowa State University Alloyed with cobalt, samarium is used as a permanent magnet, Sm 2 Co 17 -SmCo 5 . Samarium is also used as a burnable poison in nuclear reactors, as a phosphor, and in catalysts and ceramic capacitors. Samarium oxidizes slowly in air at room temperature. Storage in an inert atmosphere or vacuum is recommended. Turnings can be ignited easily. Finely divided samarium should not be handled in air. Structure [...]... Physics and Diagram Chemistry of the Actinides, A.J Freeman and G.H Lander, Ed., Elsevier, 1987 574 J.A Lee, R.O Evans, R.O.A Hall, and E King, J Phys Chem Solids, Vol 11, 1959, p 278-283 575 J.-M Fournier and R Troc, Bulk Properties of the Actinides, Chapter 2 in Handbook on the Physics and Chemistry of the Actinides, A.J Freeman and G.H Lander, Ed., Elsevier, 1985 Plutonium (Pu) Compiled by M.B Brodsky,... NpCd11, and NpPd3 have been prepared in this fashion (Ref 572) Mechanical Properties Hardness 346 HV Elastic modulus Shear modulus, 80 GPa; bulk modulus, 118 GPa References cited in this section 571 J.A Lee, P.G Mardon, J.H Pearce, and R.O.A Hall, J Phys Chem Solids, Vol 11, 1959, p 177-181 572 H.A Eick and R.N.R Mulford, J Chem Phys., Vol 41, 1964, p 147 5 -147 8 573 U Benedict, Handbook on the Physics and. .. Laboratory, U.S Department of Energy, Iowa State University Scandium is used as a neutron window or filter in reactors It is also used in high-intensity lamps because of the multilined spectrum of incandescent scandium vapor Turning of scandium can be ignited and will burn white hot Finely divided scandium should not be handled in air Ingots of pure scandium can be stored in air Structure Crystal structure... Properties Unknown Magnetic Properties Magnetic susceptibility Unknown Magnetic permeability Unknown Optical Properties Color Silvery white, sometimes with golden cast Emissivity Unknown Nuclear Properties 209 Ac through 232Ac) are radioactive The longest-lived isotope, 227Ac, has a halflife of 21.773 years and decays by β- emission (98.62%) and α emission (1.38%) It is the most abundant isotope, and. .. Gschneidner, Jr and B.J Beaudry, Ames Laboratory, U.S Department of Energy, Iowa State University Terbium is used as a phosphor and in magnetostrictive materials (Tb0.3Dy0.7Fe2) and catalysts Amorphous Tb-Co alloys are used as magnetooptic storage devices Terbium will remain shiny in air at room temperature Turnings can be ignited and will burn white hot Finely, divided terbium should not be handled in air... Gschneidner, Jr and B.J Beaudry, Ames Laboratory U.S Department of Energy, Iowa State University Yttrium is used in magnesium alloys and oxidation-resistant alloys; it is also used in garnets and ferrites for electronic components Yttrium is a host material for rare earth phosphors, including the red color (Eu) in color television screens Yttrium oxide is used to stabilize cubic zirconia for structural and electronic... 4 K along and >30 T at 4 K along Magnetic transformation temperature Ordering temperatures at 14 K (cubic sites) and 106 K (hexagonal sites) Optical Properties Color Metallic silver Spectral hemispherical emittance Solid, 43.7% for λ= 645 nm from 852 to 1074 °C; liquid, 43.7% for λ= 645 nm at 1075 °C Nuclear Properties Thermal neutron cross section 5600 b Chemical Properties General... metal results in the formation of at least two hydrides, NpH2 and NpH3 Neptunium hydride decomposes when heated in vacuum above 300 °C, yielding finely divided pyrophoric neptunium metal Phase diagrams for the Np-Pu and Np-U alloys all exhibit a common feature: the complete miscibility between γ neptunium and γ uranium and between γ neptunium and ε plutonium Several intermetallic compounds of neptunium... however, it is superconducting at 0.050 and 18.6 GPa Magnetic Properties -4 -4 Magnetic susceptibility Volume (mks units) at 24 °C: 2.466 × 10 Along crystal axes: 2.490 × 10 along a axis; -4 2.419 × 10 along c axis Optical Properties Color Metallic silver Nuclear Properties Thermal neutron cross section 24 b Chemical Properties General corrosion behavior Scandium remains shiny in air at room temperature;... structural and electronic ceramics, and as an oxide dispersant in superalloys; it is a major component in the high-temperature oxide superconductors (YBa2Cu3O7-x) Yttrium tarnishes slowly in air at room temperature Turnings can be ignited quite easily and burn with great evolution of heat Finely divided yttrium should be handled with great care and should be kept away from air and oxidizing agents Structure . multilined spectrum of incandescent scandium vapor. Turning of scandium can be ignited and will burn white hot. Finely divided scandium should not be handled in air. Ingots of pure scandium can be stored. additive in ferrous alloys to scavenge sulfur, oxygen, and other elements, and to strengthen magnesium alloys. It is also used as a laser material and glass-coloring agent, and in petroleum cracking. Gschneidner, Jr. and B.J. Beaudry, Ames Laboratory U.S. Department of Energy, Iowa State University Yttrium is used in magnesium alloys and oxidation-resistant alloys; it is also used in garnets and ferrites