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Precipitation strengthening plays a vital role in enhancing the mechanical properties of metallic materials, typically achieved through heat treatment. However, deformation-induced precipitation (DIP) in multicomponent alloys (MAs) without the assistance of annealing is rarely reported, owing to their inherent high entropy and sluggish diffusion effects. This work reveals the significant formation of nanoscale and microscale precipitates in the dual-phase Fe49.3Co23Ni23C0.85Mn1Si2.85 MA triggered by surface severe plastic deformation (SSPD) through industrial shot blasting. The SSPD process leads to the formation of ultrafine gradient structures comprising nanocrystalline and submicron-crystalline zones. Submicron SiO2 precipitates emerge at the interfaces of both these zones, while various Mn5Si3 and Si nanoparticles precipitate within the nanocrystalline zone. This phenomenon can be ascribed to the high density of generated substructures, the accelerated diffusion of atoms, and the reduction in solid solubility limits in the SPD-driven non-equilibrium state.

In the context of the growing research interest in multi-component alloys (MAs) and their exceptional performance under extreme environments, the high-temperature oxidation resistance and applications of MAs have attracted significant attention in the field of metallic materials. While the cost-effective and mechanical properties of Co-free MAs are of great importance, their oxidation resistance remains insufficiently understood. In this work, we designed multiple heterogeneous structures within a cast dual-phase Cr30Fe30Ni30Al5Ti5 MA by tailoring the Al and Ti ratio, which consists of body-centered-cubic (BCC) grains reinforced by multi-scale nanoprecipitates (i.e., L21, B2, and η phase) and an L12-strengthened face-centered cubic (FCC) skeleton. Isothermal oxidation experiments at 800 °C, 1000 °C, and 1200 °C with varying exposure durations were conducted. The oxidation kinetics at 800 °C and 1000 °C followed a parabolic law, while both low weight increment and oxidation rate confirm remarkable oxidation resistance. At 800 °C, the oxides mainly consist of Cr2O3 and Al2O3, while are dominated by (TiO2 + Cr2O3) and the mixed oxides of Al2O3, TiO2, and Ti2O above 1000 °C. Importantly, the inability to form a continuous Al2O3 oxide scale at higher temperatures led to a deterioration in oxidation resistance. These findings offer valuable insights into underlying mechanisms contributing to oxidation resistance for Co-free MAs.

High-entropy alloys (HEAs) have attracted considerable attention for their exceptional microstructures and properties. Discovering new HEAs with desirable properties is crucial, but traditional design methods are laborious and time-consuming. Fortunately, the emerging Machine Learning (ML) offers an efficient solution. In this study, composition-microhardness data pairs from various alloy systems were collected and expanded using a Generative Adversarial Network (GAN). These data pairs were converted into empirical parameter-microhardness pairs. Then Active Learning (AL) was employed to screen the Al-Co-Cr-Cu-Fe-Ni system and identify the eXtreme Gradient Boosting (XGBoost) as the optimal ML master model. Millions of data training iterations employing the XGBoost sub-model and accuracy evaluations using the Expected Improvement (EI) algorithm establish the relationship between HEA compositions and microhardness. The proposed sub-model aligns well with experimental data, wherein four Al-rich compositions exhibit ultra-high microhardness (>740 HV, with a maximum of ∼780.3 HV) and low density (

Recent investigations have demonstrated that the plasticity of bulk metallic glasses (BMGs) at room temperature can be improved by artificially introducing both macroscopic and microscopic defects. In this work, both surface grooves and multiple shear bands (MLSBs) are concurrently introduced into the surface of a Zr65Cu15Ni10Al10 BMG employing an ultrasonic bonding machine, whose sizes are also tailored by tuning gas pressures and times. After surface treatment, MLSBs appear around grooves due to the pre-plastic deformation, while numerous nano-scale crystals resulting from thermal-induced nanocrystallization appear within the grooves, leading to the emergence of hierarchical structural heterogeneities. As a result, the strength and plasticity are effectively enhanced compared to as-cast samples when suitable experimental parameters are adopted. The plastic deformation mechanisms change from single main shear banding to multiple shear banding. Therefore, the serrated plastic behaviors exhibit a transition from chaotic to self-organized critical dynamics after surface treatment, confirming the modification of the shear banding instability. The present study provides a viable method to tailor the mechanical properties of BMGs and sheds light on their dynamic plastic deformation behaviors.

The glass-forming ability (GFA), thermal stability and crystallization kinetics of (Cu0.5Zr0.5)100-xFex (x = 2.5, 5, 7.5, 10 and 12.5 at.%) amorphous alloys were studied in detail. As Fe concentration increases, the GFA and thermal stability decrease first and then increase. The excessive Fe addition significantly deteriorates the GFA due to the precipitation of the FeZr2 phase. Interestingly, with increasing Fe concentration, the crystallization products gradually transit from Cu10Zr7 and CuZr2 to B2 CuZr phase, indicating that Fe addition can effectively enhance the thermal stability of B2 phase. Simulation results show that Fe atoms may be dissolved into the B2 lattice substituting Cu sites and decrease the formation energy, which is similar to Co–or Zn-added CuZr-based alloys. Non-isothermal crystallization behaviors of Cu–Zr–Fe amorphous alloys are well described by the Šesták-Berggren (SB) model instead of the John-Mehl-Avrami (JMA) model due to the multi-phase formation (low Fe concentration) or the nucleation and growth of B2 phase (high Fe concentration). These results could help with the understanding of further stabilizing B2 CuZr phase and the fabrication of high-performance CuZr-based composites.