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[Display omitted] • The as-deposited AlCrFeCoNiCu 0.5 films were annealed at 500 °C for up to 72 h. • Four new phases were formed during the 72 h of annealing. • The formation of a new heterogeneous nanocomposite thin film was revealed. • A 30% enhancement of mechanical properties was achieved after 72 h annealing. • The as-annealed thin films exhibited superior thermal stability. High entropy alloy (HEA) films offer excellent mechanical properties due to their random solid solution structure. However, their large grain boundary volume fraction can cause thermal instability, resulting in phase decomposition that affects their high-temperature performance. Nevertheless, it remains an interesting question whether phase decomposition can be used as a processing tool to create new HEA materials. In this study, AlCrFeCoNiCu0.5 HEA thin films were fabricated and annealed at 500 °C for up to 72 h. The 72-hour annealed thin film exhibited a 30 % increase in mechanical properties, exceeding most other HEA thin films. Characterization using X-ray and electron microscopy revealed a decomposition-induced phase transformation, which produced four new phases, including Cu-rich FCC phase, Cr-rich BCC phase, and ordered B2 phase of AlNi and FeCo. The enhanced mechanical properties were due to back stress strengthening and BCC + B2 phase strengthening. The 72-hour annealed thin film also showed excellent thermal stability through a new round of annealing, exhibiting a low variation in microstructure and chemical composition after being annealed at 500 °C for 100 h. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Sc/Zr/Ti/Er modified Al-Cu alloy was successfully fabricated by wire-arc directed energy deposition technology. • The fine equiaxed grain structure was obtained due to the heterogeneous nucleation caused by the primary Al3X dispersoids. • Homogenization prefabricates more Al3X dispersoids, which promote the transition from θ″ to θ′ precipitate. • Homogenization ripens the existing pores, resulting in a better tensile isotropy. In this study, a novel Sc/Zr/Ti/Er-modified 2219 aluminum alloy was designed and wall-shaped components were then fabricated by wire-arc directed energy deposition (DED). Due to the heterogeneous nucleation promoted by primary Al 3 X dispersoids, the as-deposited alloy exhibits a highly equiaxed fine grain structure. Two heat treatment schedules were conducted to tailor the strength and thermal stability of the alloy. Compared with the classical T6 heat treatment, the additional homogenization step before the T6 heat treatment (HT6) prefabricated more Al 3 X dispersoids, which indirectly promoted the transition from θ″ precipitates to θ′ precipitates, resulting in a slight reduction in strength. However, this homogenization step helps to avoid the aggregation of pores by promoting pores ripening and significantly alleviates the anisotropy of ductility. In addition, the better thermal stability of the HT6 heat treated alloy is due to more Al 3 X dispersoids and finer θ′ precipitates with high coarsening resistance caused by the segregation of Sc and Mn at the θ′/Al interface during thermal exposure. In general, the wire-arc DEDed micro-alloyed 2219 Al alloy exhibits a promising combination of strength and ductility after heat treatment and its mechanical properties are superior to those of the wrought micro-alloyed Al-Cu alloys. [ABSTRACT FROM AUTHOR]

[Display omitted] • Compact and nanogranular ZrCu/O films were deposited by pulsed laser deposition and annealed to investigate thermal stability. • Nanogranular films crystallize at 300 °C, while the crystallization of compact films occurs >420 °C. • The Young's modulus and hardness increase with annealing temperatures due crystallization process, reaching 180 and 14 GPa for nanogranular films. • The residual stresses of compact films increase with annealing temperature, while for nanogranular ones they reach a maximum at 420 °C, indicating a complete crystallization. • The evolution of structural/mechanical properties is studied, considering film morphology, local chemistry and free volume. Binary ZrCu nanocomposite amorphous films are synthetized by pulsed laser deposition (PLD) under vacuum (2 × 10−3 Pa) and 10 Pa He pressure, leading to fully amorphous compact and nanogranular morphologies, respectively. Then, post-thermal annealing treatments are carried out to explore thermal stability and crystallization phenomena together with the evolution of mechanical properties. Compact films exhibit larger thermal stability with partial crystallization phenomena starting at 420 °C, still to be completed at 550 °C, while nanogranular films exhibit early-stage crystallization at 300 °C and completed at 485 °C. The microstructural differences are related to a distinct evolution of mechanical properties and residual stress, with compact TFMGs showing the highest values of Young's modulus (157 GPa), hardness (12 GPa), strain rate sensitivity (0.096), and local residual stress (+691 MPa) upon annealing at 550 °C, while nanogranular films reach the maximum values of mechanical properties at 485 °C followed by relaxation at higher temperatures due to complete crystallization. We show that PLD in combination with post-thermal annealing can generate different families of amorphous films with varying nanoscale morphologies, resulting in tunable mechanical properties and thermal stability, which can thus be used for designing novel film configurations for different fields of application. [ABSTRACT FROM AUTHOR]

[Display omitted] • The mechanical properties and thermal stability of nanostructured columnar Zr 100-x Cu x thin film metallic glasses were investigated and compared to those of homogeneous films. • Crystallization temperature, hardness and elastic modulus were found to be mostly dependent on composition and local atomic order rather than from film nanostructure. • Viscoplastic behavior show high influence on both film composition and nanostructure, with columnar Zr-rich films showing higher tendency toward serrated flow deformation. • Resistance to cracking is higher for Cu-rich and homogeneous films thanks to the higher density of full icosahedral atomic packing, while interfaces favored crack initiation. Thin film metallic glasses (TFMGs) are a novel class of materials showing a mutual combination of large plastic deformation in tension (>10% strain) and superior yield strength up to ∼ 3.5 GPa, which make them ideal candidates for applications such as flexible electronics. Nevertheless, a clear relationship between the atomic structure and mechanical properties of TFMGs has not yet been achieved. In particular, the role of composition in determining a different local atomic order and the effect of nanostructure on TFMGs properties must be further investigated. In this work, the mechanical properties and thermal stability of several amorphous Zr 100-x Cu x TFMGs with either compact or fine columnar nanostructure were studied. The mediating role of composition in controlling crystallization temperature and hardness is here reported, which was found to increase from 4.6 to 7.7 GPa with increasing Cu content from 26 to 76 at.%. Moreover, plastic behavior and fracture resistance are shown to be highly dependent on both composition and nanostructure, with the Cu-rich and homogeneous film able to withstand elongation up to 2% strain before crack initiation. These results underline how atomic structure changes induced by composition can effectively influence TFMG properties, while demonstrating an approach to tune their behavior for various technological applications. [ABSTRACT FROM AUTHOR]