No abstract

No abstract

The crystallization and nanoindentation behavior of a Zr–10Al–5Ti–17.9Cu–14.6Ni (at.%) bulk amorphous alloy (BAA) were studied. Resulting from the kinetic nature of phase transformation in multicomponent alloys, the crystallization path is complex. Despite the complexity of different crystallization paths, the main final crystallized product in the Zr-based BAA is Zr2Cu. Young's modulus and hardness of the BAA were found to increase with an increase in annealing temperature. The observed mechanical properties were correlated with the microstructure of the material. Also, in the present paper, both the observed crystallization and nanoindentation behavior are compared with existing data. Zr-based BAAs exhibit a ratio of hardness to Young's modulus (H/E ratio) of about 1/10, suggesting the interatomic bonding in the alloys is close to being covalent.

Crystal and interfacial structures of oxide nanoparticles and radiation damage in 16Cr-4.5Al-0.3Ti-2W-0.37 Y 2 O 3 ODS ferritic steel have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. Oxide nanoparticles with a complex-oxide core and an amorphous shell were frequently observed. The crystal structure of complex-oxide core is identified to be mainly monoclinic Y 4 Al 2 O 9 (YAM) oxide compound. Orientation relationships between the oxide and the matrix are found to be dependent on the particle size. Large particles (> 20 nm) tend to be incoherent and have a spherical shape, whereas small particles (< 10 nm) tend to be coherent or semi-coherent and have a faceted interface. The observations of partially amorphous nanoparticles and multiple crystalline domains formed within a nanoparticle lead us to propose a three-stage mechanism to rationalize the formation of oxide nanoparticles containing core/shell structures in as-fabricated ODS steels. Effects of nanoparticle size and density on cavity formation induced by (Fe 8+ + He + ) dual-beam irradiation are briefly addressed.

The tribological behavior of a Zr–10Al–5Ti–17.9Cu–14.6Ni (at.%) bulk amorphous alloy, in both the as-cast and annealed states, was investigated using nano-scratch tests, including ramping load scratch and multiple sliding wear techniques. The crystallization sequence of the alloy was also characterized. Mechanical properties, such as Young's modulus, hardness, friction coefficient, and tribological wear were measured. These properties were found to vary with microstructure. In general, an increase in annealing temperature results in an increase in hardness, which in turn produces a decrease in friction coefficient but an increase in wear resistance. Samples having a structure consisting of supercooled liquid matrix with dispersed nanocrystalline particles exhibit the best wear performance.