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Examines the structure and magnetic properties of nanostructured PrCo[sub 7-x]Ti[subx] of Pr(Co,Ti)[sub7] phase alloy. Administration of mechanical milling and subsequent annealing; Coercivity of the material; Influence of the high uniaxial anisotropy field of the Pr(Co,Ti)[sub 7] phase.

• Fine uniformly dispersed broken precipitates were obtained by ECAP. • The dislocation and broken precipitated phase enhanced the uniform corrosion. • The corrosion rate of AA8176 was reduced at 0 °C with ECAP technology. Electrochemical tests and immersion experiments were employed to investigate the corrosion behaviors of the Al-Fe alloy (AA8176) processed by equal channel angular pressing (ECAP) in 3.5 wt% NaCl solution at different temperature (25 °C and 0 °C). It was worked out that after ECAP, with the reduction of grain size, the fragmentation and uniform distribution of precipitated phases increased the number of pitting corrosion but reduced its size, the increase of grain boundary density and the reduction of precipitated phase aggregation decreased the degree of intergranular corrosion. AA8176 changed from local corrosion to uniform corrosion, which provides a new idea to improve the corrosion resistance of Al-Fe alloys. [ABSTRACT FROM AUTHOR]

High-entropy FeCoNiAl 0.5 alloy was produced and subjected to heat treatment at different temperatures (400, 600, and 800 °C). The microstructure evolution, magnetic properties and mechanical properties of the alloy were found to be highly dependent on the annealing temperature. The as-cast alloy was composed of FeCoNi-riched matrix (face-centered cubic structure) and the Al-riched region (body-centered cubic structure). After annealed at 400 °C, Al–Ni-based ferromagnetic rod-like precipitates with body-centered cubic structure were abundantly produced within the matrix, improving saturation magnetization (M s), coercivity (H c) and hardness. Increasing the annealing temperature to 600 °C, not only gave rise to a higher number density of the rod-like precipitates, but also to the formation of some nanosized spherical precipitates. This microstructure feature is more effective in strengthening the material (achieving a peak hardness of ~304 HV) but at the same time results in slight declination of M s and H c. When the annealing temperature was up to 800 °C, the most strengthening nanoscale precipitates dissolved, and the hardness of the alloy was reduced accordingly. The main strengthening mechanisms are discussed, and a good combination of mechanical and magnetic properties under optimized heat treatment may be available. [ABSTRACT FROM AUTHOR]

Nanocrystalline materials are known to possess excellent radiation resistance due to high fraction of grain boundaries that act as defect sinks, provided they are microstructurally stable at such extreme conditions. In this work, radiation response of a stable nanocrystalline Cu-Ta alloy is studied by irradiating with 4 MeV copper ions to doses (close to the surface) of 1 displacements per atom (dpa) at room temperature (RT); 10 dpa at RT, 573 and 723 K; 100 and 200 dpa at RT and 573 K. Nanoindentation results carried out for samples irradiated till 100 dpa at RT and 573 K show exceptionally low radiation hardening behavior compared to various candidate materials from literature. Results from microstructural characterization, using atom probe analysis and transmission electron microscopy, show a stable nanocrystalline microstructure with minimal grain growth and a meagre swelling in samples irradiated to 100 dpa (~0.2%) and 200 dpa at RT, while no voids in those at 573 K. This radiation tolerance is partly attributed to the stability of Ta nanoclusters due to phase separating nature of the alloy. Additionally, the larger tantalum particles are observed to undergo ballistic dissolution at doses greater than 100 dpa and are eventually precipitated as nanoclusters, replenishing the sink strength, which enhanced material's radiation tolerance when exposed to high irradiation doses and elevated temperatures. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The precipitate evolution, strength and corrosion resistance of an Al–Zn–Mg–Cu alloy processed by cryorolling, warm rolling and final aging have been investigated. A large number of spherical Zn-rich GP zones formed after warm rolling. In-situ transmission electron microscopy (TEM) observation indicated that the GP zones are stable during aging treatment and can serve as nuclei for subsequent precipitates, leading to homogeneous distribution of precipitates in the matrix after aging. TEM results also showed that ultrafine subgrains were developed in the deformed microstructure during aging. The high density of precipitates and dislocations combined with grain refinement contribute to the higher strength of the thermo-mechanically treated alloy compared with the peak-aged alloy. On the other hand, the η phase with C15 cubic structure having ‧‧‧RR‧‧‧ stacking is found in the thermo-mechanically treated alloy and is different from one with C14 hexagonal structure having ‧‧‧RR−1‧‧‧ stacking that is commonly observed in conventionally aged alloys, where R and R−1 represent rhombic layer and the relatively 180°-rotated rhombic layer, respectively. The transition from ill-defined stacking to C15 stacking and further to C14 stacking is observed in the structure of a η phase. Besides, the combination of warm rolling and aging can avoid the formation of continuous grain boundary precipitates, which is beneficial to the corrosion resistance of the alloy. [ABSTRACT FROM AUTHOR]

In this work, a nanocrystalline (NC) Cu-10at.%Ta alloy is irradiated with helium at different temperatures to assess the stability and effectiveness of Ta nanoclusters in trapping helium and suppressing swelling. Advanced microstructural characterization of the room-temperature irradiated specimens indicated the presence of small He-bubbles (∼1-2 nm) at the peak damage depth mainly at the core and along the interface of Ta nanoclusters with Cu matrix. Few bubbles were found along grain boundaries, with much smaller bubbles homogenously distributed within the copper lattice. High-temperature irradiation exhibited bubbles of ∼3-5 nm, which were primarily associated with nanoclusters as compared to other locations, with no observed faceting of the bubbles. Atom probe analysis confirmed helium partitioning to the Ta nanoclusters indicating the effective entrapment of these He atoms. [Display omitted] [ABSTRACT FROM AUTHOR]