We describe a group of alloys that exhibit "super" properties, such as ultralow elastic modulus, ultrahigh strength, super elasticity, and super plasticity, at room temperature and that show Elinvar and Invar behavior. These "super" properties are attributable to a dislocation-free plastic deformation mechanism. In cold-worked alloys, this mechanism forms elastic strain fields of hierarchical structure that range in size from the nanometer scale to several tens of micrometers. The resultant elastic strain energy leads to a number of enhanced material properties.Mechanical properties, such as strength, of metallic materials are strongly affected by metallurgical processes such as heat treatment and plastic working, which bring modifications in the microstructure. On the other hand, these processes have no substantial effect on physical properties such as elastic modulus and thermal expansion. The reason for this is that the changes that can be affected by plastic working and heat treatment do not extend to interatomic bonds or electronic states.We present a group of alloys that exhibit multiple "super" properties and drastic changes in physical properties after plastic working at room temperature. These alloys simultaneously offer super elasticity, super strength, super coldworkability, and Invar and Elinvar properties. The alloys consist of Group IVa and Va elements and oxygen and share the following three electronic magic numbers: (i) a compositional average valence electron number [electron/atom (e/a) ratio] of about 4.24; (ii) a bond order (Bo value) of about 2.87 based on the DV-X␣ cluster method, which represents the bonding strength (1-3); and (iii) a "d" electron-orbital energy level (Md value) of about 2.45 eV, representing electronegativity. The properties emerge only when all three of these magic numbers are satisfied simultaneously. Various alloy composition combinations meet these criteria, such as Ti-12Ta-9Nb-3V-6Zr-O and Ti23Nb-0.7Ta-2Zr-O [mole percent (mol %)], wherein each alloy has a simple body-centered cubic (bcc) crystal structure. In order to exhibit these properties, each alloy system requires substantial cold working and the presence of a certain amount of oxygen, restricted to an oxygen concentration of 0.7 to 3.0 mol %.Typical properties of the alloys are shown in Fig. 1 for samples before and after cold swaging with 90% reduction in area (4). Tensile stress-strain curves shown in Fig. 1A indicate that cold working substantially decreases the elastic modulus and increases the yield strength and confirm nonlinearity in the elastic range, with the gradient of each curve decreasing continuously to about 1/3 its original value near the elastic limit. As a result of this decrease in elastic modulus and nonlinearity, elastic deformability after cold working reaches 2.5%, which is at least double the value before cold working. Generally, large elastic deformations that occur in so-called "super-elastic alloys" are known to be reversible martensitic transformations resulting from deformation, d...

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High-temperature creep in undoped Al2O3 and La2O3- or Y2O3- or Lu2O3-doped Al2O3 with a grain size of about 1 µm is examined in uniaxial compression testing at temperatures between 1150 and 1350 °C. The high-temperature creep resistance in Al2O3 is highly improved by the rare-earth oxide doping in the level of 0.045 mol %, and the creep rate is suppressed in the order La2O3 <Y2O3 <Lu2O3. Rare-earth ions in each doped Al2O3 are found to segregate in Al2O3 grain boundaries without forming amorphous phase or second-phase particles. The activation energy for creep in undoped Al2O3 is estimated to be 410 kJ/mol, while it is about 800 kJ/mol in the three rare-earth oxide-doped Al2O3. The grain boundary diffusivity must be highly reduced by the segregation of the dopant cation in Al2O3 grain boundaries.