Corrosion Behavior of a Sputtered K38G Nanocrystalline Coating with a Solid NaCl Deposit in Wet Oxygen at 600 to 700°C

A nanocrystalline coating of K38G alloy was obtained by means of magnetron sputtering. The corrosion behavior of cast K38G alloy and its sputtered nanocrystalline coating with a solid NaCl deposit in dry air or wet oxygen at 600 and 700°C have been studied and compared. The results indicated that the mass gain of the coating is higher than that of the cast alloy at 600 and 700°C. Therefore, nanocrystallization reduced the corrosion resistance at these temperatures. Furthermore, the mass gains of the coating and the cast alloy with a NaCl deposit in wet oxygen were less than that with a NaCl deposit in dry air. The relevant corrosion mechanisms are discussed.     

非化学计量LaNi5型储氢合金的性能

采用富La混合稀土与Ni、Co、Mg等元素组合，获得了一种非化学计量LaNi5型储氢合金、用金相、XRD和SEM-EDX等方法分析了该合金的组织结构，研究了合金的气相储氢特性以及电化学性能，结果表明：在1.6MPa氢压和温度29℃下，该合金的储氢量达到1.58%（质量分数），该合金的放电容量为380mAh/g。经300次循环后容量保持率为55%，该合金的基体是CaCu5型结构的LaNi5相，但有第二相（LaMg)Ni3析出，这种第二相的形成是导致该合金大容量的关键。     

表面电沉积合金层提高碳钢齿轮的接触疲劳强度研究

 接触疲劳破坏是齿轮的主要失效形式之一． 在45#钢齿轮齿面电沉积Ni-P-Co合金层，可以显著提高其接触疲劳强度．同时，对合金层的表面形貌，表面粗糙度、显微硬度和疲劳点蚀坑形貌特征等进行了分析．     

REHEATING TEMPERATURE CONTRAST AND MICROSTRUCTURES OF 7075 Al ALLOY CAST BY LIQUIDUS SEMI-CONTINUOUS CASTING

In this study, reheating of liquidus semi-continuous cast billets of 7075 Al alloy was carried out in a resistance furnace, and the temperature contrast of the outer and the center of the reheated billets was investigated, then the reheating microstructures were investigated. Results show that: the difference of temperature between the outer and center is small and the difference of their microstructures are also small. During reheating at 576℃ the spheroidization of grains is significant after 5min and no rosettes are visible after 20min by optical microscopy. Similar observations were madeon materials reheated at 596℃, but the ripening process is faster. The grains growup to 30-60μm, fine enough for thixoforming.     

Recovery retardation in equal channel angular pressed Al–Zr alloy during friction stir welding

The effect of Zr on reduction of hardness and microstructure in an FS weld of equal channel angular-pressed Al alloy was investigated. Zr addition to Al suppressed dynamic recovery in the thermomechanically affected zone and enabled retention of the high hardness of the ECA-pressed material throughout the weld.     

Rapid determination of the fracture toughness of metallic materials using circumferentially notched bars

Three types of material whose fracture toughness tests were previously performed by using circumferentially notched bars, namely (1) a dual-phase steel with three different morphologies; (2) an Al-Zn-Mg-Cu-wrought alloy; and (3) Al-Si-cast alloys with three different Si contents, were investigated in terms of accuracy and reliability of the testing method. Also, the advantages of using circumferentially notched bars for fracture toughness determination of metallic materials were discussed. With the help of stress concentration factors, which are associated with the bluntness of the notch, correction factors for the fracture toughness calculations are derived. The corrected fracture toughness values are found to be close to the uncorrected ones, implying that the testing procedure is reliable.     

原始组织及加热方式对Al-5.8wt%Cu合金熔化行为的影响

利用DSC分析手段，研究了具有3种不同凝固组织的Al-5.8wt%合金在7种不同加热方式下的熔化开始温度和熔化热，发现凝固组织中存在的非平衡共晶在加热过程中大部分扩散溶解，溶入基体，剩余部分参与共晶熔化，其熔化开始温度与组织状态无关，随加热速度的增大略有升高，溶解部分的体积分散与组织状态和加热方式有关，随加热时间和非平衡相表面积的增大而增大。     

混合稀土对AZ91镁合金在NaCl溶液中的腐蚀行为影响

通过静态失重法、极化曲线和交流阻抗测试研究了混合稀土 (Re)对AZ91镁合金腐蚀行为的影响。结果表明 :Re的加入使AZ91微观组织得到改善 ,减缓了AZ91镁合金在NaCl溶液中的腐蚀     

低碳钢热浸Zn-0.15%Ni合金镀层组织及第二相粒子

采用热浸Zn-Ni合金镀锌方法，在含0.03%-0.36%Si的低碳钢上获得Zn-Ni合金镀层，研究了镀浴中Ni含量和钢中Si含量对镀层中δ相和ζ相生长速率的影响，以及Zn-Ni合金镀层η相中的第二相粒子即Zn-Fe-Ni三元化合物Γ2相粒子的形成和长大过程，结果表明，在Zn-0.15%Ni镀浴中，含硅0.03%-0.215%钢镀层的ζ相明显受到抑制，δ相厚度略有增加，Γ2相粒子的形成和长大过程包括ζ相的溶解，Γ2相的形核和成比例吸收铁，镍而长大。