钛基复合材料相对于钛合金具有更高的硬度、强度和耐磨性,可以进一步扩大钛合金在航空航天、海洋、医疗等领域的应用范围.现阶段钛基复合材料的制备方法可以分为两大类:第一,传统方法(例如熔炼和铸造).该方法存在着能耗大、成本高的问题.第二,激光选区熔化技术.该技术具有加工时间短、成形精度高、不需要制备模具的优点,但在加工过程中还存在着容易球化、开裂、降低成形件塑性等缺点.本文综述了当前国内外钛基复合材料的研究进展,包括增强体以及工艺参数调控对显微组织、成形质量及性能的影响,并结合现阶段研究现状对后续发展方向进行一定的讨论和展望.

This paper aims to research the influence of the addition of boron carbide ceramic particle enhancer on the grain shape and microstructure of commercially pure titanium (CP-Ti) during laser additive manufacturing process. It is found that during SLM process of B 4 C/CP-Ti, the reinforced particles B 4 C react with CP-Ti to produce prismatic TiB and whisker-like TiB and granular TiC. The in-situ synthesized TiC and TiB extremely improve the microhardness of the SLM-processed Ti composite from 213.9 to 513 HV 0.5 , but drastically reduced its plasticity in comparison to CP-Ti, which is of great significance for further popularization of titanium matrix composites.

针对国内企业滚丝工艺上下料过程中自动化水平低及效率低下问题,以4自由度机械手为研究对象,根据滚丝机实际的上下料流程,设定一系列中间过渡点,将其坐标值转化为各关节角度值,在MATLAB中运用spapi函数对其进行B样条插值,得到连续、平滑的关节角度变化曲线,从而完成上下料过程关节空间的轨迹规划.在ADAMS中创建机械手模型,将机械手关节角度变化曲线作为驱动函数,设置相应约束和载荷后对其进行动力学仿真,得到机械手末端的运动轨迹及腰部结构运动过程中的角位移、角速度、角加速度及力矩曲线.仿真结果表明,机械手能够实现与滚丝工艺的配合,完成预定的上下料任务,可为4自由度机械手的设计和研究提供一定的理论参考.

Aluminum matrix composites reinforced with graphene nanoplatelets (GNPs) were prepared by continuous casting and subsequent rolling. Al-GNPs master alloy, prepared by ball milling and cold pressing, was added into Al melts to fabricate the composites. Microstructure evolution of the composites were observed using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron back scattered diffraction (EBSD). GNPs distributed uniformly in the as-cast specimen and then transformed into fibers in the rolling direction after deformation and finally a lamellar structure formed in the composites. Raman spectra showed that the structural damage of GNPs mainly came from ball milling. The interface between GNPs and Al was well combined in general while a few microcracks were observed, which reduced the ductility of the composites and no adverse aluminum carbide (Al4C3) was detected at the interface. Stacking faults were observed interior of the aluminum grain, which may due to the existence of plentiful interface introduced by GNPs. Fracture observation revealed that the load transferred from Al matrix to GNPs. The ultimate tensile strength of Al-0.2 wt% GNPs composites was about 36.8% higher than that of pure Al with the same casting and rolling process, which should result from the lamellar structure and load transfer, while the conductivity of the composites decreased slightly, indicating that interface scattering between Al and GNPs is very limited. The investigation results show that Al GNPs composite is potential for high strength and high conductivity application.

高强度铝包钢芯高导电率铝绞线采用了高强度铝包钢线替代传统的镀锌钢线和普通的铝包钢线作为加强芯,与高导电率铝线组成新型的节能导线.与同规格的钢芯高导电率铝绞线相比,高强度铝包钢芯高导电率铝绞线在机械强度、节能降耗、防腐等方面具有更优越的性能,导线的拉重比更大,导线的弧垂特性更好,将为我国架空输电线路建设节能化设计提供新的选择.

哈郑工程黄河大跨越标段首次使用900 mm2大截面特高强度钢芯高强度铝合金绞线。分析了大截面特高强度钢芯高强度铝合金绞线的制造工艺要点,总结了质量控制难点,分析了传统工艺生产的产品质量情况,根据技术要求针对性地制定了改进措施,解决了900 mm2大截面特高强度钢芯高强度铝合金绞线质量控制问题。通过工艺改进,铝合金单线导电率稳定达到53%IACS,绞后铝合金单线强度稳定达到310 MPa,同时铝材料中含氢量和含杂量分别降低了60%和70%以上,保证了导线应用的节能性和安全性。

Microstructure and properties of Al-0.30Zr and Al-0.30Zr-0.08Y (mass fraction, %) alloys were investigated by electrical conductivity measurements, microhardness tests, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Micron-sized primary Al3Y phases form within grains and at grain boundaries simultaneously as product of eutectic reaction in as-cast Al-Zr-Y alloys. The addition of Y obviously accelerates the precipitation kinetics of Al3Zr (L1(2)) in Al-Zr-Y alloys. The Al-Zr-Y alloys exhibit greater electrical conductivity during aging due to formation of increased volume fractions of Al-3(Zr,Y) precipitates. In ternary Al-Zr-Y alloys, spheroidal L1(2)-structured Al-3(Zr, Y) precipitates with increased number density and smaller mean radius were observed. The Al-0.30Zr-0.08Y alloys show improved recrystallization resistance compared with Al-0.30Zr alloys

Precipitation strengthening in Al-Yb, Al-Zr and Al-Zr-Yb alloys aged isochronally between 100 and 550 degrees C was investigated. The Al-0.08 at.% Zr-0.03 at.% Yb alloy shows double-peak age strengthening behavior and obtains its second peak hardness of 379 MPa at 475 degrees C, which illustrates significant precipitation strengthening and thermal stability. The critical coherency transition radius of Ll(2)-ordered Al-3(Zr,Yb) precipitates is larger than that of Al3Yb. The synergetic effect of Yb and Zr on the precipitation evolution in Al-Zr-Yb is discussed. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The effects of Y on the precipitation evolution and recrystallization of Al–Zr alloys were investigated. The results show that the addition of Y obviously accelerates the precipitation kinetics of Al3Zr with L12 structure in Al–Zr–Y alloys. The number density of Al3(Zr,Y) precipitates is nearly one order of magnitude larger than that of Al3Zr. Smaller Al3(Zr,Y) precipitates near grain boundaries keep relatively high number density in Al–0.30Zr–0.08Y, whereas Al3Zr precipitates show decreased number density and larger radius towards the grain boundaries in Al–0.30Zr. Precipitate free regions adjacent to grain boundaries in Al–0.30Zr–0.08Y are much narrower than that in Al–0.30Zr. The Al3(Zr,Y) precipitates exhibit slower coarsening kinetics at 500°C as compared with Al3Zr. The recrystallization temperature of Al–Zr–Y alloys is about 50°C higher than that of Al–Zr alloys.

The study and application of aluminum alloy conductors gradually become the development trend of overhead conductors along with the improvement of manufacturing capacity and engineering applications of overhead conductors in China.The fabrication technologies of high-quality aluminum alloy rod for electric purpose are investigated based on the analysis of dehydrogenation and deslagging of aluminum melt.The conclusion could be provided as reference for aluminum alloy wire production.