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In order to improve the manufacturing efficiency of high-chromium superalloys, an innovative extreme high- speed laser metal deposition (EHLMD) process was used. The growth behavior of precipitated phases, high-temperature mechanical properties, wear resistance, and corrosion resistance of EHLMD K648 superalloy were investigated and compared with conventional laser metal deposition (CLMD) using transmission electron microscope, tensile tester, wear tester and electrochemical workstation, respectively. The results reveal that the precipitated phase size in EHLMD K648 superalloy is significantly smaller than that in CLMD K648 superalloy. Moreover, EHLMD K648 superalloy demonstrates higher tensile strength at 700 °C, superior wear resistance, and excellent corrosion resistance compared to CLMD K648 superalloy. Consequently, the K648 superalloy manufactured through EHLMD technique exhibits favorable comprehensive properties.

• A CALPHAD-aided strategy is implemented to design a high-performance Ni 45.9 Fe 23 Cr 23 V 4 Nb 3 Mo 1 B 0.1 (at.%) medium entropy alloy strengthened by D0 22 nanoparticles. • The newly designed alloy exhibits excellent mechanical properties at both room and intermediate temperatures, with ultimate tensile strength and fracture elongation of ∼845 MPa and 27.5 % at 700 °C, respectively, and ∼589 MPa and 24.3 % at 800 °C, respectively. • The superior combination of strength and ductility over a wide temperature range is primarily attributed to the high-density interactions of planar dislocation configurations (mainly stacking faults) and the shearable D0 22 nanoparticles. • Anomalous deformation twinning at 800 °C can be activated due to the localized stress concentration, the locally low stacking-fault energy, and especially the high diffusion rate at grain boundaries. Precipitation-strengthened medium/high-entropy alloys (MEAs/HEAs) have great potential for high-temperature applications. In this study, we designed a novel Ni 45.9 Fe 23 Cr 23 V 4 Nb 3 Mo 1 B 0.1 (at.%) MEA alloy, hardened by the D0 22 (Ni, Fe, Cr) 3 (Nb, V)-type nanoprecipitates, with an excellent strength-ductility combination from room to elevated temperatures. Specifically, the tensile strengths, at 700 and 800 °C, could be maintained as high as 845 and 589 MPa, respectively; meanwhile, elongations at all testing temperatures exceeded 25 % without any intermediate-temperature embrittlement. The temperature-dependent deformation mechanisms were unraveled using multi-scale characterizations, which involved profound slip planarities, such as stacking fault (SF) networks and deformation twins (DTs). Furthermore, the critical resolved shear stress (CRSS) to initiate SFs in both face-centered cubic (FCC) and D0 22 phases was evaluated, and the possible reasons for the origin of anomalous DTs at 800 °C were discussed in detail. The main findings demonstrate that the shearable D0 22 nanoparticles can provide the FCC matrix with considerable dislocation storage capacity, reinforcing strain hardening at ambient and intermediate temperatures. This work provides fundamental insights into the controllable design and deformation mechanisms of high-performance D0 22 -strengthened MEAs/HEAs. [Display omitted] [ABSTRACT FROM AUTHOR]

To improve the wear resistance of CoCrFeNi high-entropy alloys (HEAs) for a wider range of industrial applications, the alloying strategy was applied to CoCrFeNi HEA by doping Mo element in various ratios, and CoCrFeNiMox(x = 0, 0.2, 0.5, and 1.0) HEA deposits were fabricated by cold spray. The microstructure evolution, mechanical properties, and tribological properties of cold-sprayed CoCrFeNiMoxHEA deposits were systematically investigated. The results showed that Mo0, Mo0.2, and Mo0.5deposits have a face-centered-cubic (FCC) single structure, while Mo1.0deposit was composed of FCC matrix and hard brittle phases. The doping of Mo element into CoCrFeNi HEA deposits significantly increased the hardness due to the enhanced solid solution strengthening and precipitation strengthening. As a result, the anti-wear properties of Mo-doped CoCrFeNi HEA deposits were gradually improved with the increase in Mo ratios. To be specific, the Mo1.0deposit exhibited the lowest specific wear rate of 5.1 × 10−5mm3/N·m, which was reduced by 94.9% in comparison to the Mo0deposit. Overall, the current study proposes a new strategy to manipulate the mechanical properties of cold-sprayed HEA deposits by alloying.

• A series of novel (Ni 2 Co 2 FeCr) 92- x Ti 4 Al 4 Si x (x = 0, 1, and 2 at%) high-entropy superalloys (HESAs) was developed. • Mitigated intergranular embrittlementwas achieved in the Si-doped HESAs at 700 °C. • Si addition induced a remarkable improvement in the oxidation resistance of HESAs at 700 °C. • Our findings provide a new strategy for designing high-performance HESAs for practical applications. Ti-bearing high-entropy superalloys (HESAs) often suffer from severe intergranular embrittlement and terrible oxidation degradation at intermediate temperatures. Here we showcase that minor Si addition can effectively mitigate the intergranular embrittlement and improve the oxidation resistance of the a (Ni 2 Co 2 FeCr) 92 Ti 4 Al 4 HESA at 700 °C simultaneously. Experimental analysis revealed that the intergranular G phase induced by 2 at% Si addition can effectively suppress the inward diffusion of oxygen along grain boundaries at 700 °C, thus enhancing the tensile ductility of the alloy from ∼8.3% to ∼13.4%. Besides, the 2 at% Si addition facilitated the formation of a continuous Al 2 O 3 layer during oxidation, contributing to a remarkable reduction in the growth rate of the oxide scale to a quarter of the Si-free HESA. Our results demonstrate that Si can be a favorable alloying element to design advanced HESAs with synergistically improved thermal-mechanical performance. [Display omitted] [ABSTRACT FROM AUTHOR]

• Abrasive wear is the dominant wear mode. • The fretting wear can not only reduce its thickness but also introduce cavities into the oxide grain boundaries. • The fretting wear alters the matrix microstructure underneath the oxide scale, forming a nano-grained layer. • The nano-grained layer accelerates the Cr consumption in the near surface matrix. The worn scars on Alloy 690 after the fretting corrosion testing in simulated pressurized water reactor (PWR) secondary water have been comprehensively analyzed by scanning transmission electron microscopy (STEM) and transmission Kikuchi diffraction (TKD). The high-quality characterization results experimentally show that the fretting wear accelerates the corrosion of Alloy 690 in two approaches. The first one is to break the integrity of the oxide scale by introducing cavities at the oxide grain boundaries. The second one is to alter the microstructure of the underneath matrix, forming a nano-grained matrix layer. The increased grain boundary density in this layer can accelerate the consumption of Cr in the near-surface matrix. The loss of oxide scale integrity and the accelerated Cr consumption are believed to contribute to the deteriorated corrosion resistance of Alloy 690 during the fretting corrosion process. [Display omitted] [ABSTRACT FROM AUTHOR]

High chromium superalloy K648, additive-manufactured by extreme high-speed laser metal deposition (EHLMD) process, was heat treated by solution and then cooled at different cooling rates achieved by different conditions in this study. The investigation focused on the impact of solution cooling rates (water-cooling (WC), air-cooling (AC) and furnace-cooling (FC)) on the microstructure and mechanical properties of EHLMD K648 superalloy. As the solution cooling rates decrease, it was observed that grain sizes, carbide, and α-Cr grew larger. Simultaneously, the carbides at the grain boundary evolved from a discontinuous granular shape to a chain-like shape, while α-Cr transformed from short needle to a short rod shape. Concurrently, the quantities of secondary γʹ phase diminished, but the size of secondary γʹ phases enlarged as the cooling rate decreased. Additionally, a significant amount of small granular tertiary γʹ phase emerged in the FC superalloy. The microhardness of the EHLMD superalloy exhibited a substantial increase with the decrease of the solution cooling rate, to the point that the microhardness of FC superalloy reached 429 HV. The ultimate tensile strength and yield strength increase, but the elongation decreases significantly, with the ultimate tensile strength of FC superalloy reaching 1058.3 MPa. The fracture of EHLMD K648 superalloy gradually transformed into ductile fracture to ductile and brittle mixed fracture as solution cooling rates decreased.

The oxidation behavior of a newly developed single-crystal L12-strengthened Co-rich high-entropy superalloy, Co41Ni35Al11.5Ta2.5Cr4Ti6(at%), was investigated systematically in air at 800, 900, and 1000°C. The results reveal that this alloy demonstrates excellent oxidation resistance from 800 to 1000°C. At 800°C, a bilayer oxide scale was formed, consisting of a TiO2/Al2O3mixture layer and a Cr2O3layer. The continuous but non-dense Cr2O3layer could not effectively inhibit internal oxidation and internal nitridation. Complex hierarchical-structure oxide scale formed at 900 and 1000°C, mainly composed of spinels, Cr2O3, TiTaO4, and Al2O3. Surprisingly, an anomalous improvement in oxidation resistance was found in a temperature range from 900 to 1000°C. Specifically, the formation of a more complex and continuous five-layer oxide scale at 1000°C, particularly the bottom compact Al2O3layer, endows the alloy with exceptional resistance to oxidation at 1000°C.

Printing Cu alloys with simultaneously high strength and high electrical conductivity by laser powder bed fusion remains a challenge. In conventionally manufactured Cu alloys, nanoprecipitates form through alloying elements to impart significant strengthening effects while having a lesser impact on electrical conductivity. However, the ultrahigh cooling rate of laser powder bed fusion promotes the supersaturated solid solution of alloying elements, resulting in severe lattice distortion in the Cu matrix and a significant compromise in electrical conductivity. Therefore, it is vital to select Cu alloying elements that substantially prevent the formation of a supersaturated solid solution in laser powder bed fusion to achieve outstanding strength while maintaining sufficient electrical conductivity. In this study, we fabricated a Cu-O alloy with high strength (491.6 MPa) and high electrical conductivity (68.0 % IACS) using laser powder bed fusion. The alloy features a cellular microstructure in which Cu2O nanoprecipitates are configured orderly as the cellular boundary. This cellular microstructure can promote strength by impeding dislocation motion and maintain a high electrical conductivity by preserving a longer free path for conductive electrons. This study explores the potential of combining the alloy composition and extreme process conditions of laser powder bed fusion to provoke unique microstructures and overcome the dilemma between strength and electrical conductivity in Cu alloys.

High chromium superalloys have good overall mechanical properties and are widely used in critical hot-end components. The current manufacturing process still faces the problem of low forming efficiency. Extreme high-speed laser metal deposition (EHLMD) is a new and efficient additive manufacturing technology that can quickly and directly shape the direct forming of difficult-to-process materials. However, EHLMD still possesses some inter-layer defects in EHLMD alloy due to its excessively fast scanning speed, implying that there is potential for further improvement in its properties. Hot isostatic pressing (HIP) as a post-heat treatment is primarily used for the removal of defects in additive manufacturing components. In this study, the defects, microstructure, and properties of the EHLMD K648 superalloy using Micro-CT, XRD, SEM and TEM under HIP treatment were investigated. The results show that the porosity of the HIP EHLMD K648 superalloy decreased, and slender needle-shaped α-Cr phase, γ′ phase and coarse M6C carbides were precipitated. The tensile strength of the HIP EHLMD K648 superalloy increased by about 240 MPa. However, its plasticity was reduced. To further improve the plasticity of the HIP EHLMD K648 superalloy, subsequent heat treatment was carried out. The outcomes of this study are expected to promote the manufacturing of high-quality chromium superalloys and the development of EHLMD technology.

Ti−6Al−4V alloy was fabricated via selective laser melting (SLM) to improve its corrosion resistance for implant. The microstructure and electrochemical corrosion behavior were investigated using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), electrochemical test and contact angle test. It can be found that the as-selective laser melted (as-SLMed) Ti−6Al−4V alloys show βcolumnar microstructure in building direction and nearly circular checkerboard microstructure in scanning direction, while the wrought and wrought+HT samples exhibit equiaxed microstructure. The as-SLMed Ti−6Al−4V alloy exhibits better corrosion resistance than the wrought and wrought+HT samples due to hydrophobicity, high grain boundary density and uniform distribution of alloying elements in simulated artificial saliva at 37 °C.

Laser butt welding was carried out for the joining of 5A06 aluminum alloy sheet by using 6 KW fiber laser. The effect of welding speed on the surface morphology, microstructure, micro-hardness, tensile strength and porosity were studied by means of optical microscopy (OM), a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS), a Vickers hardness tester and a universal mechanical tensile test. The results show that the weld macro morphology tends to be smooth and the surface defects are reduced with an increase in welding speed. The heat-affected zone was very small due to the large cooling rate. The columnar dendrites grow from the fusion line along the direction of the temperature gradient. The microstructure of the weld zone was in the form of equiaxed grains. The micro-hardness of the weld was lower than that of the base material. The micro-hardness and the tensile strength were gradually increased with an increase in welding speed. When the welding speed is 12 mm × s-1, the micro-hardness and the tensile strength were increased to 96.5 % and 56.2 % of the base mental, respectively. The porosity ratio decreased at first, and then increased with the increase in welding speed. The lowest porosity ratio was 1.99 % when the welding speed was 12 mm × s-1. In summary, the quality of the weld was better when the welding speed was 12 mm × s-1.

Heterogeneous-structured (HS) materials have drawn particular attention due to their extraordinary strength-ductility combinations. Benefiting from the large thermal gradient and high cooling rate, additive manufacturing (AM) enables structural and compositional heterogeneity at the multiscale, which provides new routines for high-performance HS materials. Here, we successfully fabricated a cellular-structured CoNiCrFeAlTi-based high-entropy alloy (HEA) by using the directed-energy deposition (DED) technology. Subsequent thermal treatment produces a distinctly different microstructure consisting of single-phase (face-centered cubic, FCC) interior and dual-phase (FCC + L12) wall, which leads to an ultrahigh tensile strength of ~1148MPa combined with a large ductility of ~28%. We attribute the high strength to the pronounced ordering strengthening from high-density L12-type precipitates in the wall while the large ductility primarily comes from the improved plastic deformation stability via hetero-deformation-induced strain hardening and deformation-induced stacking faults (SFs). Our current work is expected to open up a new area for designing high-performance HS multiple-principal-element alloys.

In this work, the oxidation behavior of Inconel 718 superalloy fabricated by selective laser melting was investigated in the CO2atmosphere at 1000 and 1100 °C. Results show that the structure of the oxide scales is strongly dependent on the grain position (grain boundary and grain interior) and the oxidation temperature. It forms six-layer and four-layer oxide scales at the grain boundary region after 300 min oxidation at 1000 and 1100 °C, respectively, producing three-layer oxide scales in the intragranular area. The formation mechanisms of the oxide scale were discussed. Additionally, the Kirkendall voids and internal oxidation in the matrix preferentially form at 1100 °C.

A novel Al-Ce-Mg alloy with an in-situ nano-network structure and improved tensile properties was fabricated using laser powder bed fusion (LPBF). The microstructure of the as-fabricated alloy exhibited an extremely fine eutectic Al/Al11Ce3co-continuous structure, i.e., Al11Ce3intermetallics with an in-situ nano-network surrounding the interconnected Al matrix. It forms an equiaxed grain in the scanning direction (SD) and columnar grain in the building direction (BD). The yield strength (YS) and ultimate tensile strength (UTS) in SD and BD are 300 ± 11.5 MPa, 438 ± 6.9 MPa, and 303 ± 5.0 MP, 442 ± 3.3 MPa, about three times higher than those of as-cast alloy. The elongations (El) are 9.3 ± 0.7% and 6.2 ± 1.2% in SD and BD, respectively, exhibiting anisotropy. The perfect interfacial bonding between the Al11Ce3phase and Al matrix combined with nano-scale network structures provided a strong ability to hinder the propagation of microcracks formed within Al11Ce3particles. Besides, the alloy retained outstanding strength at elevated temperatures with 200 MPa at 300 °C and 100 MPa at 400 °C, which may be attributed to the heat resistance of nano-network Al11Ce3intermetallics and the extremely low diffusion coefficient of Ce in the Al matrix. This work provides a new idea for developing heat-resistant aluminum alloys with a good combination of strength and ductility via additive manufacturing (AM) processing technique.

The Fe-B-Al alloy containing 0 to 10.0 wt.-% Al was melted in a vacuum induction furnace. Effects of the aluminum addition on the microstructure and properties of Fe-B-Al alloys were studied by means of optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), hardness testing and MMG-500 type pin-on-disk high temperature vacuum wear testing. The results showed that the as-casted microstructure of the aluminum-free Fe-B alloy consisted of a-Fe, Fe2(B,C), and Fe23(B,C)6type borocarbides. However, the as-casted microstructure of the Fe-B-Al alloy consists of a Fe3Al type intermetallic compound when the aluminum content is more than 6.0 wt.-%. Compared with the aluminum-free Fe-B alloy, parts of the borocarbide networks are broken, and the fracture tendency became more obvious with the increase of the aluminum content. Boron is mainly distributed over the borocarbide. Aluminum is mainly distributed over the matrix and Fe3Al type intermetallic compound. Compared with the aluminum-free Fe-B alloy, the addition of a small amount of aluminum reduces slightly the hardness. The hardness gradually increased with the further increasing of the aluminum content. The hardness reached 48.1 HRC when aluminum content was 10.0 wt.-%. The high temperature wear resistance of Fe-B-Al alloy gradually increased with the increase of the aluminum content. When the aluminum content reached 10.0 wt.-%, the high temperature wear resistance of the alloy was the best.

This paper presents the multi-roller contact roller-gear cam reducer. It’s a special kind of the indexing roller-gear cam that changes the stopping stage of the indexing cam to zero and chooses the equal-velocity law. And with multi-roller contact the carrying capacity is greatly improved. In this paper, we created the 3D solid model of the main components of the reducer: the cam, the turntable and the rollers. After that, we used the FEA software ANSYS Workbench to calculate the static structural behavior and the results showed us the weak or dangerous part of the mechanism so that we can optimize the structural. However the static structural behavior does not always shows the working condition. Thus we calculated the flexible dynamic behavior of the reducer and it showed us vividly that which part is weak and we could see the real deformation and stress distribution of the structural while working. Then we can pay more attention to these parts.

On the basis of parallelogram linkage, this paper introduced the working principles of a kind of new transmission mechanism:crank-group driving mechanism, its three basic configurations and their advantages and dis-advantages.

To drive multiple parallel-axis to rotate synchronously，this paper put forward a kind of new transmission mechanism——crank-group driving mechanism， introduced the concept of it and its working principles，and demonstrated the feasibility of its movement .

In order to meet the requirements of synchronous output among multiple parallel-axis in some light industry machinery and avoid the traditional transmission ways’ defects, we put forward a kind of new transmission mechanism which is called the crank-group driving mechanism. This paper introduced the mechanism's inquiry process as follows: the movement that we need is a kind of uniform transmission , we choose the configurations of mechanism according to the requirements of movement; after comparison among various kinds of mechanism, we choose the parallelogram linkage as the prototype of the new mechanism, and the new mechanism is a evolution of it; we demonstrated the movability of the new mechanism from the point of view of freedom, and introduced the configurations of new mechanism.

This paper illustrated the characteristics of parallelogram linkage，introduced the origin of the crank-group driving mechanism and its design principles, analyzed some problems of virtual constraints，and verified the feasibility of this mechanism.

This paper put forward a kind of crank-group driving mechanism on the basis of parallelogram mechanism , introduced its concept, design process, and analyzed the feasibility of its movement. It can drive multiple parallel-axis synchronously, and it is a new way of transmission.

The key component of the spindle box for using the fuzzy optimization method for high-speed vertical machining center was optimized. Through the analysis of the fuzzy information of the components, the membership functions of the constraint were determined, and the satisfactory results were obtained according to the characteristics of the actual problems or decision-makers intention. Through fuzzy finite element method, the optimal solution in the space was adjusted, the design of multiple choices was provided for designers, and the favorable conditions for other design of parts were created.

Box-taking mechanism is an important part of automatic cartoner, it also is a “bottleneck” in automatic cartoner. After analyzing the process of box-taking and the key movements for automatic cartoner, designed a new kind of box-taking mechanism with double cam five-bar combined mechanism. Combining five-bar mechanism and cam advantages, the mechanism can be realized the trajectory with the demand of velocity and gesture. The detailed and interchangeable gas circuit also be designed, which reduced the complexity of replacing the seal rings. Practical result shows that the mechanism could execute the box-taking gesture quickly and smoothly.

Researches and analyzes an advanced cigarettes in this paper, with the help of 3d modeling software pro/E image intuitively emulation produce its motion curves, and obtain the displacement, velocity and acceleration curve, Using the mechanism motion and kinematics analysis diagram, the mechanism kinematical process is analyzed which is laid a certain foundation for the further improved cigarette pusher device.

In general, production control of digital workshops is a complicated systematical engineering. Because of lacking the methods and means of acquiring the manufacturing data in real time, the traditional production control methods cannot satisfy the real production control requirement of digital workshops. In this paper, we put forward an intelligent control system for digital workshop production. The main contributions include three aspects: Firstly, we introduce and adopt Radio Frequency Identification (RFID) technology as a means to acquire the manufacturing information in real time produced by the bottom-level manufacturing devices. Secondly, we develop the wcPML (workshop control with Physical Markup Language) and utilize it to act as a media to realize the information visualized description and transmission between the top-level control systems and bottom-level manufacturing sites of workshops. Thirdly, we adopt Java Web technology and wireless LAN to build the infrostructure for the intelligent control system for workshop production. Some key enabling technologies for the intelligent control system also are presented and described following with some concluding remarks.