In this study, the corrosion properties of a novel Co40Cr20Ni30Al4.5Ti5Mo0.5 high-entropy alloy at different annealing temperatures were investigated through electrochemical techniques and tests conducted in an extreme environment of high-temperature and high-pressure CO2 containing 3.5 wt% NaCl. The results show that alloys annealed at temperatures ranging from 700 to 1000 degrees C recrystallized with different degrees. Notably, annealing at 800 degrees C significantly enhances corrosion resistance, as evidenced by a lower passive current density (i(pass) = 5.75 x 10(-7) A/cm(2)), wide passive potential range (Delta E = 716 mV(SCE)), and high pitting potential (E-pit = 500 mV(SCE)). Under extreme conditions of 200 degrees C and 6 MPa CO2, the alloy retains favourable mechanical properties and demonstrates exceptional corrosion resistance, can be attributed to the formation of nanoscale grain size (similar to 0.81 mu m) at 800 degrees C, a thicker and uniformly dense passive film (similar to 4.33 nm).

Three types of Fe-30 wt%Mn-8wt%Al-1wt%C steel with different Cu contents were prepared, and the effects of the Cu content on the microstructure and corrosion properties of the austenite-based low-density steel were systematically investigated. The experimental results indicate that the addition of an appropriate amount of Cu is conducive to the nucleation and growth of austenite while also refining the carbides. However, the addition of an excessive amount of Cu is added results in a sharp decrease in the number of carbides. Additionally, Cu does not fully dissolve into the austenite matrix but rather accumulates at the grain boundaries in its elemental form. This distribution creates a potential difference from the austenite matrix and results in a synergistic corrosion effect with the carbides, leading to preferential corrosion of the grain boundaries and an increased degree of corrosion on the surface of the matrix.

The corrosion properties of five nonisothermally aged (NIA) Al-Zn-Mg-Cu alloys with different heating rates are studied and compared with those of the T6-treated alloys by electrochemical experiments and weight loss test. The results show that reducing the heating rate results in an increase in the corrosion resistance of the alloy. The aging treatment at a heating rate of 10 degrees C/h results in an alloy with an excellent corrosion resistance and a low corrosion current density. Additionally, the hardness of the alloy is similar to that of the alloy treated with T6. Coarse precipitates are obtained by 10 degrees C/h aging treatment, with the grain boundaries (GBs) transferring to intermittent phases with narrow precipitation-free zones (PFZs). Therefore, this approach effectively prevents anodic dissolution and improves the corrosion resistance of the alloy. These findings suggest that NIA can enhance the mechanical properties and corrosion resistance of an alloy. Additionally, the 10 degrees C/h aging process reduces the processing time by approximately 50 %, compared to that of the T6 treatment, offering a costeffective alternative. These results provide valuable insights into the processing of large aluminium components.

This study primarily discusses a unique topology for constructing a double full bridge circuit. The study establishes a push-pull inverter model and analyses the balance circuit in its architecture. This allows the power supply to initiate the balance circuit and ensures the TPS (Taiwan Photon Source) booster magnet power supply operates smoothly in a safe and balanced voltage region when magnet energy is recovered. We employ the approach of adding Y circuits to mitigate the impact of common mode (CM) noise. Adding a Y circuit effectively suppresses the common-mode noise generation, improving the quality of the output current of the TPS dipole magnet power supply at low currents state and ramping the beam current energy from 150 MeV to 3 GeV. Furthermore, the reproducibility and stability of the injection point can enhance the injection efficiency of the TPS booster magnet power supply. This study presents the results obtained from these efforts.

Short-range order (SRO) has made a splash in the recent research on multi-principal element alloys (MPEAs), among which the equiatomic VCoNi alloy was regarded as the most potential prototype. However, in addition to disputes over SRO, there is still a lack of agreements on the phase stability and deformation mechanism of the VCoNi alloy, which should be addressed before the SRO can be independently analyzed. To this end, microstructural evolutions with increasing long-term annealing temperatures (from 700 to 1,200 degrees C) were first inspected in detail to determine critical temperatures for phase transitions unambiguously. Our results revealed that the VCoNi alloy was still dominated by the face-centered-cubic (FCC) structure with a minor kappa phase at 900 degrees C and became a single FCC solid solution at above 910 degrees C. Subsequently, by carefully examining dislocation configurations and stacking fault (SF) widths in the FCC phases annealed at 900 degrees C and 1,200 degrees C, significant variations in local stacking fault energy (SFE) were unveiled, and the overall SFE decreased with increasing annealing temperature. Combined with the state-of-the-art density function theory (DFT)-based lattice Monte Carlo (MC) simulation, we demonstrated how the rise/decline in SFE can be explained by the greater/lower degree of SRO. This research would not only offer new perspectives for recent controversies over phase stability, deformation mechanism, and SRO characterization technique using electron diffraction but also shed light on the intrinsic relationship between SRO and local stacking fault energy of MPEAs.

Modern engineering has long been in demand for high-performance additive manufactured materials for harsh working conditions. The idea of high entropy alloy (HEA), medium entropy alloy (MEA), and multi-principal-element alloy (MPEA) provides a new way for alloy design. In this work, we develop a Co42Cr20Ni30Ti4Al4 quinary MEA which exhibits a superiority of mechanical properties over a wide temperature ranging from 77 to 873 K via selective laser melting (SLM) and post-heat treatment. The present MEA achieves an excellent ultimate tensile strength (UTS) of 1586 MPa with a total elongation (TE) of 22.7% at 298 K, a UTS of 1944 MPa with a TE of 22.6% at 77 K, and a UTS of 1147 MPa with a TE of 9.1% at 873 K. The excellent mechanical properties stem from the microstructures composed of partially refined grains and heterogeneously precipitated L12 phase due to the concurrence of recrystallization and precipitation. The grain boundary hardening, precipitation hardening, and dislocation hardening contribute to the high YS at 298 and 77 K. Interactions of nano-spaced stacking faults (SFs) including SFs networks, Lomer-Cottrell locks (L-C locks), and anti-phase boundaries (APBs) induced by the shearing of L12 phase are responsible for the high strain hardening rate and plasticity at 77 K. Our work provides a new insight for the incorporation of precipitation hardening and additive manufacturing technology, paving the avenue for the development of high-performance structural materials.

Multi-principal element alloys (MPEAs) with body-centered-cubic (BCC) structures composed of elements of IVB, VB, and VIB usually exhibit high compressive strength and superior high-temperature performance. However, premature necking under tensile loading at ambient temperature limits their applications. Herein, we report the Hf0.5Nb0.5Ta0.5Ti1.5Zr MPEA with a single BCC phase, which performs considerable tensile plasticity by the process of strain delocalization. The formation of dispersed slip bands and two major strain localized regions suppress premature necking. The strain-localized region with a larger strain gradient realized strain delocalization during non-uniform deformation, resulting in considerable tensile plasticity (similar to 20%) with a yield strength of 922 MPa. Two dominated work hardening mechanisms were revealed. One is the geometrically necessary dislocations (GNDs) produced by non-uniform deformation which can coordinate deformation incompatibility, thus enhancing plastic deformation capability. The other is the lattice distortion which can provide an easy path for the cross slip of dislocations and realize strain delocalization. These two kinds of work-hardening mechanisms jointly contribute to the significant plastic deformation capacity of the Hf0.5Nb0.5Ta0.5Ti1.5Zr MPEA.

Cast high-entropy alloys are frequently found to have large internal tensions, compositional segregation, and shrinkage defects, which can directly prevent them from performing as intended. Proper heat treatment can modify the internal structure of an alloy and enhance its overall performance. This study describes a new nonequiatomic proportional cast Co 40 Cr 20 Ni 30 Al 4.5 Ti 5 Mo 0.5 high-entropy alloy prepared by a vacuum induction melting technique. The impacts of different annealing temperatures (700, 800, 900, and 1000 degrees C) on the microstructure evolution mechanism, mechanical properties and corrosion behaviour of the alloy are systematically examined. The results show that the heat treatment can successfully improve the overall mechanical properties and corrosion resistance of high-entropy alloys while suppressing casting defects. The alloy exhibits the best overall mechanical properties after annealing at 700 degrees C, with a yield strength of 923 MPa and a tensile strength of 1090 MPa. After annealing at a temperature of 800 degrees C, the alloy demonstrates excellent corrosion resistance, characterized by a low passivation current density, a large passivation range, and a high corrosion potential. Specifically, i pass is measured to be 4.59 x 10 -7 A/cm 2 , and E corr is -319 mV. Furthermore, the maximum Cr 2 O 3 oxide content in the alloy passivation film formed at 800 degrees C contributes to the passivation film stability.

This study establishes the groundwork for an industry-applicable, integrated nanosheet-based monolithic CFET process architecture with a gate pitch of 48nm. By introducing the middle dielectric isolation, inner spacer, and n/p source-drain isolation, the vertically stacked nFET-on-pFET nanosheet transistors yield a survival rate of over 90% and demonstrate high on-state current with low leakage, achieving a healthy six-order of magnitude on/off current ratio. This work sets the stage for further CFET development and paves the way for a practical process architecture that can fuel future logic technology scaling and PPAC advancement.

Accurately predicting the phase stabilities of high entropy alloys (HEAs) is of significance for alloy design and development. The predicted results of the existing established thermodynamic approaches have a large deviation from the actual results. To avoid this problem, a new simplifying prediction scheme is proposed and reported in this study, which was built on the experimental results of 130 HEAs combining ten elements, including Al, Co, Cr, Cu, Fe, Mn, Mo, Ni, Ti and V. Firstly, the bond enthalpies between atom pairs in condensed solid solutions (BCC or FCC) were reasonably estimated by applying the Ab-initio method. Secondly, from a thermodynamic standpoint of the correlation between the bond enthalpies and the interaction parameters, a new quantified technique of the interaction parameters between elements was established. Then, the mixing enthalpies of the solid solutions with specific crystal structures, as well as the Gibbs free energies of the intermetallic compounds, have been extracted. Thus, by contrasting the Gibbs free energies of the alloy system before and after precipitation, an overall basic approach to predicting the phase stability has been developed. This method has taken into account the change of the Gibbs free energy of the solid solution after the separation of intermetallic compounds, the calculated results have evolved into more accurate and reliable ones and can point out which kind of complex phase (Sigma phase or Laves phase) would precipitate in the HEAs, offering a fundamentally new approach with high credibility for predicting the phase stability of the HEAs.

Hetero-grain/precipitation engineering was adopted to improve mechanical properties of alloy over a wide temperature range. Partial recrystallization and L12 nanoprecipitation were simultaneously introduced into a CoCrNi-based medium entropy alloy, resulting in a heterogeneous microstructure. This kind of heterostructured alloy achieves an ultrahigh tensile strength of 1.5 GPa at 500 degrees C, and still maintains a tensile strength above 1.1 GPa at 600 degrees C. All elongations exceed 20% at-196 degrees C and elevated temperatures up to 700 degrees C, which indicates the breakthrough in temperature-dependent embrittlement encountered by many structural materials with equiaxed grain structures. Such a superior combination of strength and ductility at elevated temperatures can be ascribed to the stable deformed grains and pronounced planar defects, including stacking fault networks and deformation twins. This work demonstrates that hetero-grain/precipitation engineering can provide an effective strategy to achieve high strengths of alloys without sacrificing ductility over an extended temperature range.

Despite the widespread use of Ti6Al4V in orthopedics, the health concerns, innate bio-inert property and the pursuit of long-term implantation in the body limit its development. For these reasons, we intend to modify the chemical and physical properties of Ti6Al4V by the sputtered bioactive Ti-Ta-Nb films. All these elements exhibit great biocompatibility in human body and the Ti-Ta-Nb system can form more stable passive layer to prevent the corrosion. In this study, we evaluate the effectiveness of the surface modification for Ti-Ta -Nb system on Ti6Al4V and investigate the influence of bioactive element Ta content from 25, 33, to 50 at% by the bio-corrosion behavior, passivation, in-vitro biological analysis and invivo implantation. The results show the Ti-Ta-Nb system has higher corrosion resistance and better biological properties than Ti6Al4V. Furthermore, following the electrochemical tests and passive layer observation, with increasing Ta content in Ti-Ta-Nb system, the corrosion resistance increases. The in-vitro measurements demonstrate that the higher Ta content in this system would lead to favorable surface condition for cell viability, proliferation, differentiation and adhesion. As for the in-vivo response upon implantation, the Ta50 film demonstrates significantly greater osteointegration capability. In summary, the current results reveal that the Ti-Ta-Nb system could greatly promote the surface properties of Ti6Al4V, and Ta50 is demonstrated to be a more promising coating choice for orthopedic

The Co40Cr20Ni30Al5Ti5 multi-principal element alloy (MPEA) with heterogeneous grain structure (HGS) and nano L12 precipitates is successfully designed by cold rolling and proper heat treatment. The HGS alloy exhibits excellent corrosion resistance and passivation performance, originated from high-density grain boundaries in fine grains and abundant defects in deformed grains, which encourages surface to form a thicker and more efficient passive layer to inhibit the initial pitting corrosion. This finding indicates that the developed MPEA with HGS can possess an excellent combination of corrosion resistance and mechanical properties, providing highly positive factors for future applications.

The traditional approaches for improving corrosion resistance of alloys typically lead to the sacrifice of mechanical properties because the microstructures needed for improving corrosion resistance often contradict those for high strength. Here we demonstrate that selected laser melting (SLM), a net-shape additive manufacture technique, can maintain good mechanical properties while double the corrosion-resistance of a N-doped CoCrFeNi HEA. The SLM processed sample possesses a heterogeneous microstructure with 3D dislocation cells inside each grain. The SLM-induced 3D dislocation cell structure can provide effective diffusion paths to significantly promote Cr outward segregation, forming a thick protective Cr oxide layer, which renders excellent corrosion resistance. Furthermore, Cr segregation along cell boundaries provides numerous sites for nucleation of oxides, and stabilizes the cell structure for good mechanical properties. The strategy discovered here may also be applied to other HEAs with multiple strengthening mechanisms.

In this work, the mechanical response as a function of ageing time at 700°C for a cold-rolled complex alloy with a chemical composition of Co40Ni33Cr15Al5Ti7 (at%) was explored. The alloy exhibited an ultrafine-scaled recrystallized microstructure combined with high-content coarse L12-type ordered precipitates after a long-term aging for 100 h at 700°C. The resultant alloy demonstrated an extra strain-hardening mechanical response with yield strength of 2.1 GPa and tensile elongation of ∼12% at room temperature. By transmission electron microscopy observations, it was affirmed that the occurrence of profuse stacking faults as well as deformation induced twins during the critical plastic straining stage was mainly responsible for the observed extra strain-hardened behavior. The long-term aging process at low temperature provides a promising strategy for a precipitation-hardening complex alloy with severe deformation to obtain the superb combination of yield stress and ductility.

High-performance but low-cost structural materials with nanoscale precipitations are vitally important for engineering applications in advanced industry systems. Thus far, the classical nucleation mechanism assumes a critical nucleus of a homogeneous composition up to a sharp boundary with a large energy barrier of nucleation. A fine dispersion of nanoscale precipitates often requires strong solute supersaturations with expensive alloying additions or otherwise deteriorated strength-ductility, weldability, and fabricability. The simultaneous satisfaction of all these mutually exclusive requirements is the longstanding issue for the design of advanced materials for structural applications. In this alloy design, we have adopted a revolutionary approach of ultra-strong iron-based alloys that have resolved all these key issues through non-classical nanoscale precipitations and multi-elemental partitioning. Such an alloy design strategy offers a unique approach to control nanoscale precipitates with low solute supersaturations. Fine precipitations so designed lead to the strong enhancement of both the precipitate-dislocation interactions and work-hardening capacity, resulting with a sharp increase of the yield strength (YS) to as high as 1500 MPa and tensile ductility up to 15%. Furthermore, our design assures outstanding fabricability together with superior post-weld properties through dense nanoscale reprecipitations (similar to 10(24) m(-3)) in a well economical manner for production. The non-classical actions unfold brand new pathways for precipitation of various intermediate structures and chemistries with low energy barriers, especially useful for the design of sustainable and economical modern alloy systems.

High-entropy alloys (HEAs) are expected to possess various excellent properties due to their vast composition design space and unique core effects. Annealing treatments after cold rolling are widely discussed as an effective means to improve the overall performance of the alloy. Nevertheless, the effect of annealing treatments on the corrosion resistance of cold-deformed alloys is still somewhat controversial. Therefore, cold rolling and annealing at different temperatures are performed on the Co40Cr20Ni30Al5Ti5 high-entropy alloy to investigate the effect of annealing temperature on its corrosion behavior. The annealing temperature range covers all stages of the HEA recovery-recrystallization-grain growth (in 50 °C gradients). The experimental results show that the HEA recrystallization is fundamentally complete at 850 °C and fully austenitized at 1050 °C. The best corrosion resistance performance is observed at 850 °C, with the lowest corrosion current density (ipass) and the lightest pitting in full immersion experiments. In addition, excellent passivation properties, such as the lowest steady-state current density iss and highest passivation film growth rate, are achieved at 850 °C. Further analyses of the growth films also show that the passivation films formed at 850 °C are thicker and uniform, and additionally have the highest Cr2O3 content. Accordingly, the effects of annealing temperature on HEA corrosion resistance and passivation behavior are discussed. The superior corrosion resistance and passivation behavior at 850 °C are attributed to the coupling of grain size and passivation film composition. The current findings might guide the optimized design of future cold-deformed alloys for better corrosion resistance.

The corrosion behaviors of selective laser melted (SLMed) FeCoCrNi multi-principal element alloys (MPEAs) with carbon or nitrogen addition in 0.5 M H2SO4 solution were investigated. Both C and N addition refined the grains and introduced a heterogeneous structure in SLMed FeCoCrNi MPEA, but they had opposite effects on the corrosion behavior. The doped carbon participated as nano-sized carbides in SLMed MPEA, and localized galvanic corrosion occurred, degrading the corrosion resistance. The doped nitrogen was gathered with chromium and formed CrN chemical clusters in SLMed MPEA, and a protective passive film with a higher Cr2O3/Cr(OH)3 ratio formed, which improved corrosion resistance.

Electrochemical corrosion and stress corrosion cracking (SCC) behavior of X80 steel in the sulfurated marine environment at open circuit potential and −850 mVSCE are investigated. The results show that SCC is controlled by both anodic dissolution and hydrogen evolution, which is attributed to the HSO3− acceleration of the anodic and cathodic current density. Localized anodic dissolution leads to pits, which induce stress that promotes the initiation of stress corrosion cracks. Under a cathodic potential of −850 mVSCE, the effect of dissolution is limited, and SCC susceptibility increases because of the synergistic effect of the high HSO3−concentration and cathodic potential.

Ti-based metallic glasses have a high potential for implant applications. The feasibility of a new biocompatible Ti-based bulk metallic glass composite for selective laser melting (SLM) had been examined. Therefore, it is necessary to design a high-glass-forming-ability Ti-based metallic glass (∆Tx = 81 K, γ = 0.427, γm = 0.763), to fabricate a partial glass-formable spherical powder (the volume fraction of the amorphous phase in the atomized Ti-based powders being 73% [size < 25 μm], 61% [25–37 μm], and 50% [37–44 μm]), and establish an SLM parameter (a scan rate of 600 mm/s, a power of 120 W, and an overlap of 10%). The Ti42Zr35Si5Co12.5Sn2.5Ta3 bulk metallic glass composite was successfully fabricated through SLM. This study demonstrates that the TiZrSiCoSnTa system constitutes a promising basis for the additive manufacturing process in terms of preparing biocompatible metallic glass composites into complicated graded foam shapes.