Magnesium alloys, a novel functional material for the fabrication of fracturing tools, are being paid more and more attentions recently due to their relatively high mechanical properties and fast dissolubility ability after fracturing. In this study, the novel extruded Mg-10Gd-3Y-0.3Zr-xNi alloys will be reported and their microstructure, mechanical and corrosion behaviors will be also studied. The results show that Ni contents influence phase precipitation behaviors. With adding 0.2 wt% Ni, a large amount of Zr7Ni10 phases will be precipitated insides alpha-Mg matrix, directly leading to degradation of strength and large corrosion rate. With further increasing Ni contents, the precipitation phases can be changed from Mg5RE to 18R-LPSO structure, resulting in higher mechanical properties and faster corrosion rate. Moreover, adding Ni element also change the texture orientation by influencing the precipitation behavior of the alloys. The alloys invented in this paper have attained the highest compressive and tensile properties among all the reported dissoluble magnesium alloys. This work is beneficial in understanding the role of Ni in the magnesium alloys and provides more materials alternatives for the fabrication of dissoluble fracturing tools. (C) 2020 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.

Freestanding thin films of Mg-Li (magnesium-lithium) alloys with a Li mass fraction between 1.6% (m/m) and 9.5% (m/m) were prepared and studied with respect to their structure and degradation properties. With increasing Li content, the microstructure deviates from hexagonal Mg-Li with strict columnar growth and preferred orientation, and additional cubic Mg-Li and LiCO occur. The corrosion rate was measured in Hanks' balanced salt solution by potentiodynamic polarisation and weight loss measurements to investigate biodegradation. Influences of the orientation, phase and protective layer formation lead to an increase in corrosion from 1.6 to 5.5% (m/m) from 0.13 ± 0.03 to 0.67 ± 0.29 mm/year when measured by potentiodynamic polarisation but a similar corrosion rate for 9.5% (m/m) and 3% (m/m) of Li of 0.27 ± 0.07 mm/year and 0.26 ± 0.05 mm/year.© 2023. Springer Nature Limited.

In this work, the influence of rolling ratios on microstructural changes and corrosion behavior of an as-rolled Mg-8 wt.%Li alloy in 0.1 mol/L NaCl solution has been investigated. It revealed that with the rolling ratio being increased from 3 to 10, the alpha-Mg phases were elongated and fragmented, whilst the area fraction of exposed beta-Li phases increased. Meanwhile, the corrosion performance of the alloy decreased with the increased rolling ratios. For all the samples, their corrosion processes were quite similar and can have two stages. At the initial stage with the samples being immersed for less than 6 h, the corrosion mainly occurred in beta-Li phases. When the samples were immersed for longer than 6 h, the corrosion attack transferred to alpha-Mg phases and the hydrogen evolution rate was accelerated. (C) 2020 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.

As the lightest structural metallic materials, Mg-Li alloys have a bright development prospect in the fields of aerospace, weapon equipment, electronic technology and transportation. In this paper, the research progress of deformation processing and heat treatment of Mg-Li alloys is reviewed, with particular emphasis on the factors affecting the plastic deformation, the effects of plastic deformation on microstructural evolution and mechanical properties, and the heat treatment behavior of Mg-Li alloys. The problems existing in the scale application of Mg-Li alloys are pointed out, and the research focus of Mg-Li alloys in the future are also prospected.

Zn and its alloys have recently been used as a new class of biodegradable biomedical metals besides magnesium and iron alloys, owing to their moderate corrosion rate and good mechanical properties. In recent years, researchers have rigorously studied the design, processing, and degradation mechanism of Zn alloys, but their biocompatibility has not been well explored. Past research on the biocompatibility of Zn alloys focused on in vitro cytotoxicity, hemolysis, and coagulation, and only a few materials were implanted into animals for characterizing the histocompatibility. Biocompatibility involves complex local and systemic reactions, such as cells, tissues, blood, and immunity. In addition to the physical and chemical properties of the material, the biocompatibility is also affected by interactions between the material and body. In this paper, the chemical and phase compositions of degradable zinc alloys were analyzed, and the biological evaluation methods were clarified. In view of the recent studies on zinc alloy biocompatibility, future research directions were proposed.

锌合金由于其适宜的腐蚀速率、良好的力学性能，成为继镁合金与铁合金后的一种新型的可降解生物医用金属材料。近年来，研究者对锌合金的设计、加工制备以及降解机理进行了大量研究，但对其体内外生物相容性的研究尚不充分，仅评估了体外细胞毒性、溶血、凝血，少数材料植入动物体内进行了组织相容性的表征。然而生物相容性涉及细胞、组织、血液、免疫等复杂的局部反应和全身反应，除了材料本身的物理化学性质，还受到材料与机体相互作用的影响。本文分析了可降解医用锌合金的化学成分和物相组成，阐明了对其进行生物学评价的方法，并结合锌合金生物相容性研究现状，阐述未来的研究方向。

Porthole die extrusion is the dominant process to produce hollow profiles due to its high productivity and capacity in producing complex profiles. In this study, the finite element simulation model of porthole die extrusion of LZ91 Mg-Li alloy was established. The effects of extrusion ratio on strain, temperature and flow velocity were studied, and the welding quality was quantitatively evaluated by means of J criterion. The experiments of porthole die extrusion were carried out by varying extrusion ratios. The microstructures of as-cast, homogenized and extruded LZ91 Mg-Li alloy were examined. The results show that the materials near the bridge surface and at the bottom of the bridge have large deformation, while the materials inside the portholes have small deformation. Moreover, with the increase of extrusion ratio, the effective strain of material is increased. Due to the heat generated by plastic deformation and the heat dissipation caused by profile cooling, the temperature of the material on the top of bridge is increased, while that of the material near the die exit becomes lower. The welding quality in the central area of weld seam is lower than that in the edge area of weld seam. With the increase of extrusion ratio, the welding quality is improved. More nucleation is generated in welding zone due to its large strain, resulting in the formation of fine grains. However, the dynamic recrystallization is not complete in the matrix zone, and some coarse grains still remain. Moreover, the material temperature becomes higher with high extrusion ratio, and the phenomenon of grain growth is observed.

Magnesium alloy has a hexagonal close-packed crystal structure, and its plasticity is poor at room temperature. This is primarily due to the small number of movable slip systems at room temperature, which is prone to deformation texture. Therefore, temperature and compression deformation play an important role in the regulation of plastic deformation. In this work, AZ80 magnesium alloy was subjected to multi-pass compression deformation at a constant temperature and step-down temperature. The microstructure of the AZ80 magnesium alloy with different deformation degrees and deformation paths was observed and analyzed using EBSD. In addition, the grain boundary, dislocation density, Schmid factor, and polar figure evolution of the AZ80 magnesium alloy during hot compression deformation were primarily studied. Results show that the comprehensive effect of grain size, twinning, and texture on the plastic regulation of AZ80 magnesium alloy is better than that of single dynamic recrystallization. Moreover, three-time constant-temperature deformation (ε = 0.6) promotes dynamic recrystallization, whereas three-time step-cooling deformation (ε = 0.6) promotes plastic deformation. More 86°{101¯2} <12¯10> tensile twins are produced by reduced grain orientation difference, increased number of low-angle grain boundaries, and increased geometrically necessary dislocation density, which are important factors affecting the plastic regulation of three-time step-cooling deformation (ε = 0.6).

镁合金具有密排六方结构，可动滑移系少导致其室温塑性差，而热加工对调控镁合金塑性有重要作用。本工作对AZ80镁合金分别进行恒温、阶梯降温多道次压缩变形，利用电子背散射衍射(EBSD)技术观察分析了不同变形程度、不同变形路径下AZ80镁合金的微观组织，研究了AZ80镁合金热压缩变形过程中晶界、位错密度、Schmid因子和极图演化规律。结果表明：晶粒尺寸、孪晶、织构综合作用对AZ80镁合金塑性调控的影响优于单一动态再结晶对其塑性调控的影响，恒温三次变形(ε = 0.6) (3P)有利于发生动态再结晶，而阶梯降温三次变形(ε = 0.6) (3P)更有利于塑性变形。晶粒取向差减小、小角度晶界(LAGBs)数量增多、几何必需位错(GND)密度增加3者共同作用产生更多86°{101¯2} &lt;12¯10&gt;拉伸孪晶是影响阶梯降温三次变形塑性调控的重要因素。

Magnesium rare-earth (Mg-RE) alloy castings with a large size and complex structure exhibit versatile prospects in critical aircraft, aerospace, and defense fields owing to their ultralow density, excellent specific strength, and high-temperature resistance. The grain refinement of cast Mg-RE alloys can significantly improve their strength, plasticity, toughness, and casting performance, which are critical for expanding their applications. In this work, the grain refinement mechanism of Mg alloys by introducing RE elements and heterogeneous particles is first discussed based on the classical theory of constitutional supercooling and heterogeneous nucleation. Various grain refinement technologies for Mg-RE alloy casting using chemical and physical methods are comprehensively summarized. Further, the influence of grain refinement on the casting performance, mechanical properties, and corrosion properties of Mg-RE cast alloys is thoroughly discussed. Finally, the deficiencies and development trends of the current grain refinement of Mg-RE alloys are discussed from the point of actual application requirements.

轻质高强耐热的镁稀土(Mg-RE)合金大型复杂铸件在航空航天、国防军工装备轻量化等方面展现出独特的优势。对铸造Mg-RE合金进行晶粒细化处理能够显著改善合金的强度、塑韧性以及铸造工艺性能，对拓宽其应用领域意义重大。本文首先基于成分过冷和异质形核，探讨了稀土元素及外加颗粒对镁合金晶粒细化的影响。归纳了适用于铸造Mg-RE合金的化学、物理细化方法及其作用机制，并系统论述了晶粒细化对铸造Mg-RE合金铸造工艺性能、力学性能及腐蚀性能的影响。最后面向Mg-RE合金的实际应用需求，对其细化处理方面存在的不足和发展趋势进行了探讨。

采用OM、SEM、XRD和TEM研究了低密度Ti₂AlNb基合金热轧板在600~1100℃保温12 h微观组织的热稳定性。结果表明，Ti₂AlNb基合金原始态热轧板主要由α₂、B2以及O相组成，颗粒状的α₂相分布在B2相基体中。Ti₂AlNb基合金热轧板600℃保温12 h，颗粒状的α₂相分布在B2相基体中，B2相基体中分布着大量细小的O相板条。随着温度的升高，合金热轧板800~900℃保温12 h的微观组织由α₂、B2以及O相三相构成，α₂相颗粒逐渐球化，O相板条粗化并固溶于B2相基体中。当温度升高至950℃时，B2相基体中的O相板条消失。合金热轧板在950~1000℃保温12 h形成α₂ + B2两相区，α₂相颗粒球化并趋向于分布在B2相基体的晶界处。当温度升高至1100℃时，合金基体为B2单相，B2晶界处分布着极少量的残留α₂相颗粒。Vickes显微硬度分布结果显示，随着温度的升高，合金板材在600℃时硬度达到峰值(509 HV)，这与大量细小的O相板条有关。

Ultra-lightweight alloys with high strength, ductility and corrosion resistance are desirable for applications in the automotive, aerospace, defence, biomedical, sporting and electronic goods sectors. Ductility and corrosion resistance are generally inversely correlated with strength, making it difficult to optimize all three simultaneously. Here we design an ultralow density (1.4 g cm(-3)) Mg-Li-based alloy that is strong, ductile, and more corrosion resistant than Mg-based alloys reported so far. The alloy is Li-rich and a solute nanostructure within a body-centred cubic matrix is achieved by a series of extrusion, heat-treatment and rolling processes. Corrosion resistance from the environment is believed to occur by a uniform lithium carbonate film in which surface coverage is much greater than in traditional hexagonal close-packed Mg-based alloys, explaining the superior corrosion resistance of the alloy.

In this work, a novel computational model for the description of the temperature- and composition-dependent isotropic interfacial energy in multicomponent alloys was first developed in the framework of the CALculation of PHAse Diagram (CALPHAD) approach and implemented in a home-made code. By linking to the open-source code for interfacial energy calculation in alloys, OpenIEC, the databases for isotropic γ/liquid and γ/γ' interfacial energies in Ni-Al, Ni-Cr, Al-Cr, and Ni-Al-Cr systems were then efficiently established. After that, a direct coupling strategy between the current CALPHAD interfacial energy database and the phase-field model with finite interface dissipation was proposed and applied to three-dimensional (3-D) phase-field simulations of the primary γ dendritic growth in both Ni-Al and Ni-Al-Cr alloys during isothermal solidification. The effect of the interfacial energy on the morphology, tip growth rate, and partitioning coefficients in primary γ dendrites of binary Ni-Al and ternary Ni-Al-Cr alloys was investigated by comprehensively comparing the phase-filed simulation results using the composition-/temperature-dependent interfacial energies with those using the constant value. It is anticipated that the presently developed CALPHAD model for interfacial energy is of general validity for different multicomponent alloys and should be integrated with the phase-field model for quantitative simulation of their microstructure evolution.

Several mechanisms have been proposed to interpret the widely reported phenomenon of Mg corrosion that the hydrogen evolution rate increases with increasing anodic potential or anodic current density. This paper critically analyzed the two main mechanisms, (1) “the incomplete film univalent Mg + ion mechanism” and (2) “the enhanced catalytic activity mechanism”, aiming to clarify the current understanding of the Mg corrosion mechanism and to provide a profound insight into the Mg characteristic electrochemical behavior, anodic polarization accelerating both hydrogen evolution and Mg dissolution. It is expected that the deepened fundamental understanding from this comprehensive mechanistic review will provide a basis of practical applications for Mg alloys and open up a new way to the control of corrosion of Mg alloys in practice.