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高频脉冲电沉积镍钴合金镀层的硬度研究

许韵华曹克宁杨玉国赵宇宫晓静

中国腐蚀与防护学报

在硫酸盐电解液中,采用脉冲电源电沉积了镍钴合金。研究了电解液中CoSO4的浓度及脉冲参数对镀层中Co含量和镀层显微硬度的影响。采用SEM和XRD研究了镀层的表面形貌和微观结构。结果表明,镀层中的Co含量对镀层硬度有显著影响,当Co含量小于55 mass%时, 镀层的硬度随着Co含量的增加递增。Co含量较低时,合金由面心立方结构(fcc)的固溶体组成。

关键词: 高频 , Ni-Co alloys , Microhardness , Microstructure

电火花表面强化TC4钛合金的组织与性能

李敏 , 王宏伟 , 蔡兰蓉 , 刘鹏鑫

宇航材料工艺

以石墨为电极,分别在煤油和雾介质中对TC4钛合金(表面分别未涂覆及涂覆碳层)进行电火花表面强化.对强化层微观组织、相组成及显微硬度进行了研究.结果表明,所有强化层组织均呈菊花瓣状.合金表面涂覆碳层后强化层表面球状碳化物数量都较未涂覆时明显增加,且在煤油介质中得到的强化层中碳化物在花瓣边缘处聚集,雾介质条件下碳化物分布更为弥散、均匀.对强化层进行物相分析表明,强化相由电极C和基体Ti原位反应生成,强化层由基体α-Ti和TiC相组成.强化层表面显微硬度较原始TC4钛合金相比大幅提高,雾介质中得到的强化层显微硬度值与煤油介质中基本相同,可达800 MPa左右,但分布更为均匀,力学性能更稳定.

关键词: 电火花表面强化 , 强化层 , 微观组织 , 相组成 , 显微硬度

Si含量对Mg-8Zn-4Al-0.3Mn镁合金时效过程的影响

张春香 , 吴立鸿 , 刘晓芳 , 刘忠侠 , 关绍康

材料热处理学报

采用光学显微镜、扫描电镜(附EDAX能量分散光谱系统)和差示扫描量热仪(DSC)等分析手段研究了不同Si含量(0~1.61 wt%)对Mg-8Zn-4Al-0.3Mn(ZA84)合金时效过程的影响.结果表明,合金经固溶处理后显微硬度较铸态下提高了8%左右,其Mg2Si、τ(Mg32(Al,Zn)49)等相基本未溶入基体中.随着ZA84合金中加入Si量的增加,合金的析出相形成激活能呈增加趋势,峰值时效时间由ZA84合金的2 h左右推迟至8 h左右,析出相粗化时间较ZA84合金推迟4 h以上.合金中加入不同含量Si后其峰值时效显微硬度提高幅度为4%~12%.

关键词: 耐热镁合金 , , 时效析出 , 组织 , 显微硬度

Electrodeposition and Characterization of Ni/Ti3Si(Al)C2 Composite Coatings

Ying Liang

材料科学技术(英文)

Pure nickel and Ni/Ti3Si(Al)C2 composite coatings were prepared by electrodeposition method from an additive-free nickel Watt's bath and were characterized by X-ray diffraction, laser confocal microscopy and scanning electron microscopy. The effect of current and Ti3Si(Al)C2 concentration in the solution on the composition, grain size, preferred orientation and surface morphology of the electrodeposited coatings were investigated. (200)-oriented Ni coatings could be deposited at high current (62.5 mA), while (220)-oriented Ni coatings could be obtained at low current (25 mA). However, the presence of Ti3Si(Al)C2 particles disturbed the surface texture of Ni crystallites in the composite coatings. Based on the simulated morphology and the observed microstructure, the mechanisms for the change of preferred orientation and crystallite shapes in the presence of Ti3Si(Al)C2 particles were discussed. Moreover, microhardness and friction properties of pure nickel and Ni/Ti3Si(Al)C2 composite coatings were also compared.

关键词: Ni/Ti3Si(Al)C2 composite coatings

Microstructural and Microhardness Variation of Amorphous Fe78Si9B13 Alloy during Bend Stress Relaxation

Xifeng LI , Kaifeng ZHANG , Changli WANG , Wenbo HAN , Guofeng WANG

材料科学技术(英文)

The amorphous Fe78Si9B13 ribbons were bend stress relaxed at various temperature well below the crystallization temperature (Tx) for different time. The effect of pre-annealing on the subsequent bend stress relaxation was examined. The variation of the microstructure and microhardness during bend stress relaxation process was studied using X-ray diffraction (XRD), atomic force microscopy (AFM) and Vickers microhardness test, respectively. Curvature radius of the amorphous Fe78Si9B13 ribbons decreased with increase bend stress relaxation temperature and time. The microhardness of the stress relaxed specimens increased with time at 300℃ due to the forming of nanocrystals during bend stress relaxation. The pre-annealing reduced the decrease rate of the curvature radius of stress relaxed specimens.

关键词: Bend stress relaxation , null , null , null

Reactive DC Magnetron Sputtering Deposition of Copper Nitride Thin Film

Xing′ao LI , Zuli LIU , Kailun YAO

材料科学技术(英文)

Copper nitride thin film was deposited on glass substrates by reactive DC (direct current) magnetron sputtering at a 0.5 Pa N2 partial pressure and different substrate temperatures. The as-prepared film, characterized with X-Ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy measurements, showed a composed structure of Cu3N crystallites with anti-ReO3 structure and a slight oxidation of the resulted film. The crystal structure and growth rate of Cu3N films were affected strongly by substrate temperature. The preferred crystalline orientation of Cu3N films were (111) and (200) at RT, 100℃. These peaks decayed at 200℃ and 300℃ only Cu (111) peak was noticed. Growth of Cu3N films at 100℃ is the optimum substrate temperature for producing high-quality (111) Cu3N films. The deposition rate of Cu3N films estimated to be in range of 18–30 nm/min increased while the resistivity and the microhardness of Cu3N films decreased when the temperature of glass substrate increased.

关键词: DC magnetron sputtering , 氮化铜薄膜 , 电阻率 , 显微硬度

Mechanical assisted electroless barrel-plating Ni-P coatings on magnesium alloy

Zhaoxia PING , Juntao YUAN , Yedong HE , Xiaogang LI

金属学报(英文版) doi:10.1016/S1006-7191(08)60093-9

A mechanically assisted electroless barrel-plating Ni-P was carried out in a rolling drum containing Mg alloy specimens and ceramic balls, which was submerged in a bath containing electroless plating solution. It is demonstrated that the Ni-P coatings deposited by this novel technique have a crystallized Ni-P solid solution structure, showing fine-grains, higher hardness, and higher corrosion resistance compared with the conventional electroless plated amorphous Ni-P coatings. After heat treatment at 400℃ for 1 h, the structure of such Ni-P coatings were transformed to a structure with Ni-Ni3P double phases, and cracks in these coatings could not be observed, whereas cracks appeared seriously in the conventional electroless plated Ni-P coating after same heat treatment. Therefore, both hardness and corrosion resistance of these Ni-P coatings can be improved further by heat treatment. All of these beneficial effects can be attributed to the role of mechanical attrition during the mechanically assisted electroless barrel-plating process.

关键词: Mechanically assisted electroless barrel-plating , null , null , null , null

Nano ZrO2 Particulate-reinforced Lead-Free Solder Composite

Jun SHEN , Yongchang LIU , Dongjiang WANG , Houxiu GAO

材料科学技术(英文)

A lead-free solder composite was prepared by adding ZrO2 nanopowders in eutectic Sn-Ag alloy. Microstructural features and microhardness properties of those solders with different ZrO2 nanopowder fraction were examined. Results indicate that the addition of ZrO2 nanopowders reduced the size of β-Sn grains and restrained the formation of bulk Ag3Sn intermetallic compounds (IMCs) due to the adsorption effect of the ZrO2 particles. The Vicker's hardness of the obtained lead-free solder composites fits well with the Hall-Petch relationship. The refinement of β-Sn grains favors to improve the microhardness of composite solders.

关键词: ZrO2 nanopowders , null , null , null

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