The substantial loss of strength arising from recovery and recrystallization of the deformed microstructure limits the application of Cu-Cr-Zr alloys at elevated temperatures. In this study, DFT calculations are used to design a thermodynamically stable ternary phase composed of Cu, Zr and Hf. Based on this, the Cu–1Cr–0.3Zr–0.5Hf–0.2Si (wt.%) alloy is fabricated. In the peak-aged condition (500 °C/3h), the alloy exhibits a tensile strength of 582.36MPa and an electrical conductivity of 80.75% IACS. The recrystallized grain fraction is only 8.6% and the softening resistance temperature reaches as high as 600 °C. It is indicated that Hf addition promoted the formation of the nanoscale Cu5(Zrₓ,Hf₁₋ₓ) precipitates, which exhibit a disc-shaped morphology and coherent interfaces with the matrix, improving dislocation storage capacity. In addition, the precipitates exert a pinning effect on grain boundaries, which effectively suppresses recrystallization at elevated temperatures and improves the alloy’s thermal stability. Statistical results show that the average size of the Cr precipitates is only 5.2nm, whose good thermal stability ensures the strengthening effect. Calculation results confirm that dislocation strengthening and precipitation strengthening contribute the majority of the alloy’s tensile strength. This provides a new strategy for the development of heat-resistant Cu-Cr-Zr alloys for next-generation electromagnetic rail systems.

Copper alloys reinforced with fibers, particularly those containing Fe fibers, exhibit significant potential for various applications due to their superior mechanical strength and cost-effectiveness. In this study, a Cu-6.5Fe-0.3Mg-0.1Si alloy wire is designed and fabricated by thermo-mechanical treatment. The alloy in cold-drawn state has an impressive tensile strength of 1210 MPa, accompanied by an electrical conductivity of 47.1 % IACS, while the post-annealing alloy exhibits corresponding values of 835 MPa and 61.67 % IACS. Microstructural analysis reveals significant changes of the size, morphology and orientation in the phase and grain of the alloy during drawing and annealing. As the tensile strain increased, both the Cu matrix grains and the Fe-rich fibers (identified alpha-Fe phase) undergo substantial refinement, along with the development of highly preferred orientations < 111 >(Cu)||LD and < 110 >(Fe)||LD in the drawing direction, respectively. After the final annealing, two spherical strengthening nanoprecipitates, i.e., the DO3-ordered Fe3Si phase and the BCC-structured alpha-Fe phase precipitate in the matrix. A quantitative analysis of indicated that heterogeneous deformation-induced strengthening (HDI) between the matrix and the Fe fibers is the primary strengthening mechanisms, with contributions of 57.5 % and 47.9 % to the overall strength before and after the final annealing treatment, respectively. Consequently, the precipitation of the nano-spherical phase, the directional arrangement of the Fe fibers, and the synergistic effects of work hardening collectively contributed to the enhanced strength of the Cu-6.5Fe-0.3Mg-0.1Si alloy.

The transition of the supersonic boundary layer induced by roughness is a highly intricate process. Gaining a profound understanding of the transition phenomena and mechanisms is crucial for accurate prediction and control. In this study, to delve into the flow mechanisms of a transition in a supersonic boundary layer induced by the medium gap-type roughness, direct numerical simulation is employed to capture and analyze the transition process. Research indicates that as the flow over the flat plate passes the gap, the spanwise convergence effect leads to the formation of both upper and lower counter-rotating vortex pairs. As the flow progresses, these counter-rotating vortex pairs in the central region exhibit attenuation, with streamwise vortices developing on both sides. At a certain downstream distance, the boundary layer becomes unstable, triggering the formation of streamwise vortex legs. These streamwise vortex legs undergo further evolution, transforming into hairpin vortices and leg-buffer vortices. The formation of the central low-speed zone downstream of the roughness element is mainly attributed to the lift-up effect of the low-speed flow propelled by the central counter-rotating vortex pairs. The low-speed streaks on both sides are primarily influenced by the streamwise vortices. Through a meticulous analysis of the turbulent kinetic energy distribution and its generation mechanisms during the transition phase, this study infers that the primary sources of turbulent kinetic energy are the hairpin vortices, leg-buffer vortices, and their consequent secondary vortices. Combined with modal analysis, the study further elucidates the generation and breakdown of hairpin and leg-buffer vortices.

Lightweight materials with high strength and excellent damping capacity are of great significance for reducing weight and vibration and maintaining stability in industrial applications. However, these characteristics are usually difficult to achieve simultaneously in traditional damping materials. Here, we provide a design strategy for dual-scale interpenetrating networks. By infiltrating the viscoelastic polymer containing CrMnFeCoNi nanoalloy/carbon nanotube networks into CrMnFeCoNi high-entropy shape memory alloy foam with a three-dimensional network structure, the dual-scale CrMnFeCoNi/polymer interpenetrating phase composite was developed. When the carbon nanotube loading is 2 wt%, the composite exhibits a compressive strength of 37.2 MPa and an energy absorption capacity of 22.5 MJ center dot m(-3) (epsilon = 65 %), with a mere density of 2.528 g center dot cm(-3). In the temperature range of 20 similar to 150 degrees C, its loss factor exceeds 0.132 with a peak value of 0.206. Compared with CrMnFeCoNi foam, its compressive strength, energy absorption capacity and peak internal friction are increased by 85 %, 65 % and 156 %, respectively. The construction of dual-scale interpenetrating networks introduces high-density interfaces, and the coupling of multi-scale intrinsic damping and interface damping endows the composite with high ground-state damping. The superposition of the phase transformation peak of CrMnFeCoNi foam and the glass transition peak of polymer composite matrix enables a wide damping temperature window. This study offers a new perspective for developing high-performance damping materials.

采用色差测试、电化学测试、静态腐蚀测试、扫描电镜分析、电化学阻抗测试和X射线光电子能谱分析等方法,研究仿金Cu-Zn-Ni-Sn合金在人工海水和人工汗液中的腐蚀行为.合金在人工海水腐蚀初期的腐蚀产物层主要为较为致密的Cu2O和具有良好耐腐蚀性能的ZnO、Zn5(CO3)2(OH)6和Zn5(OH)8Cl2?H2O等氧化产物,该氧化膜两侧界面的传质过程是腐蚀反应发生的决速步骤.在人工汗液中腐蚀初期的主要腐蚀产物主要为疏松的CuO和不稳定的SnO,使其腐蚀产物膜疏松、易剥落.在人工汗液的腐蚀过程中,早期形成的腐蚀产物层会开裂,而裂纹末端界面的固相扩散决定了腐蚀反应的速率.

The corrosion behavior of imitation-gold Cu-Zn-Ni-Sn alloys with and without Al was investigated by means of color difference testing, static corrosion measurements, scanning electron microscopy analysis, electrochemical impedance measurements, and x-ray photoelectron spectroscopy analysis. The results showed that aluminum inhibited dissolution of Zn and Sn by the formation of an oxide film on the surface of the Cu-Zn-Ni-Sn alloy during corrosion, effectively improving its corrosion resistance. A transition of the corrosion product from Cu2O and Cu(OH)(2) to CuO occurred on the surface of Cu-Zn-Ni-Sn-Al alloy, and the corrosion rate of the alloy decreased with increasing corrosion time due to the formation of the oxidation film and the hydrophobic effect of Zn-5(CO3)(2)(OH)(6) in the product layer.

OBJECTIVE:To analyze the clinical characteristics, pathological features, treatment response and prognosis of patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN), so as to provide reference for reducing clinical misdiagnosis and treatment regimens.METHODS:The clinical, pathological features, treatment regimens and treatment response of 9 patients with BPDCN diagnosed and treated from January 1, 2013 to June 30,2019 in Xiangya Second Hospital of Central South University were analyzed respectively.RESULTS:The most common site of involvement in 9 patients with BPDCN was skin; the pathological features were involvement of dermis, and the highest positive immunohistochemical indexes rate were CD4, CD43, LCA, CD123, and VIM (all 100%), followed by CD56 and CD68, TDT, CD5, PAX-5, CD3, CD8, CD20; MPO and EBER of 9 patients were negative. However, Ki-67 of the 9 patients showed a medican of 77. 5% (40%-90%), which suggests that CD4, CD43, LCA, CD123, and VIM were the most sensitive antigens for diagnosing BPDCN. Of the 9 patients, 2 cases were lost to follow-up, 2 cases were untreated, and 5 cases were treated, in which 2 cases received treatment of regiment for acute lymphoblastic leukemia and 3 cases received treatment of regimen for lymphoma. The PR of clinical symptoms in the first cycle in 5 patients were 100%, and 1 patient has survived for 6 years since the disease was diagnosed.CONCLUSION:BPDCN is a rare and highly invasive lymphoid hematopoietic malignancy. The most common initial symptom of the patients is skin lesions. The most sensitive pathological indicators are CD4, CD43, LCA, VIM, and the BPDCN patients received treatment of regimens for lymphoid tumor show a better response rate.

慢性粒细胞白血病(CML)是一种发生在多能造血干细胞水平上的恶性骨髓增殖性肿瘤.靶向BCR-ABL融合基因的酪氨酸激酶抑制剂给CML治疗带来了突破,然而在治疗中仍有耐药现象的产生.笔者就其耐药治疗策略进行综述.