S.Y. Gao
,
Y.Z. Zhang
,
L.K. Shi
,
B.L. Du
,
M.Z. Xi
,
H.Z. Ji
,
null
,
null
,
null
,
null
,
null
,
null
,
null
,
null
,
null
,
null
,
null
金属学报(英文版)
Laser direct deposition (LDD) of metallic components is an advanced technology of combining CAD/CAM (computer aided design/computer aided manufacturing), high power laser, and rapid prototyping. This technology uses laser beam to melt the powders fed coaxially into the molten pool by the laser beam to fabricate fully dense metallic components. The present article mainly studies the LDD of Ti-6Al-4V alloy, which can be used to fabricate aircraft components. The mechanical properties of the Ti-6Al-4V alloy, fabricated by LDD, are obtained using the tension test, and the oxygen content of used powders and deposited specimens are measured. In the present article, it can be seen that the mechanical properties obtained using this method are higher than the ones obtained by casting, and equal to those got by wrought anneal. One aircraft part has been made using the LDD process. Because of this aircraft part, with sophisticated shape, the effect of the laser scanning track on the internal soundness of the deposited part was discussed.
关键词:
laser direct deposition
,
null
,
null
W. Chen
,
Y.Z. Zhang
,
C.J. Zhang
,
L.G. Zhu
金属学报(英文版)
The aim of this study is to simulate the solidification process of beam blank continuous casting, and then find the reasons for the typical defects of the beam blank. A two-dimensional transient coupled finite element model has been developed to compute the temperature and stress profile in beam blank continuous casting. The enthalpy method is used in the heat conduction equation. The thermo-mechanical property in the mushy zone is taken into consideration in this calculation. It is shown that at the mold exit the thickness of the shell has its maximum value at the flange tip and its minimum value at the fillet. The temperature has a great fluctuation on the surface of the beam blank in the secondary cooling zone. At the unbending point, the surface temperature of the web is in the brittleness temperature range under the present condition. To ensure the quality, it is necessary to weaken the intensity of secondary cooling. At the mold exit the equivalent stress and strain have higher values at the flange tip and at the web. From the spray 1 to the unbending point, the maximum values of stress and strain gradually move to the internal section of the flange tip and the web. However, whenever, there are bigger stress and strain values near the flange tip and the web than in the other parts, it must be very easy to generate cracks at those positions. Now, online verification of this simulation has been developed, which has proved to be very useful and efficient to instruct the practical production of beam blank continuous casting.
关键词:
beam blank
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null
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null
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null
Journal of Materials Research
The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.
关键词:
room-temperature
何恩全
,
马文会
,
刘荣辉
,
于洁
,
戴永年
稀有金属
doi:10.3969/j.issn.0258-7076.2007.04.019
采用了甘氨酸-硝酸盐法制备了La0.7Sr0.3Cr0.5-yMn0.5-zCo(y+z)O3(y, z=0.1, 0.2)系列阳极材料.借助XRD, SEM对所制备的材料进行了物相和形貌分析.XRD表明利用GNP法制得的粉体在1350 ℃烧结5 h可以形成完整的钙钛矿相;SEM分析可知所得物料颗粒呈球状,尺寸约为1 μm,且没有团聚现象.同时,XRD显示La0.7Sr0.3Cr0.5Mn0.4Co0.1O3和La0.9Sr0.1Ga0.8Mg0.2O3电解质之间具有较好的化学相容性.采用直流四探针法测试了不同组成材料在250～800 ℃温度范围内在空气中的电导率,发现该系列材料在该温度段范围符合小极化子导电机制.另外,利用直流四探针法测试了La0.7Sr0.3Cr0.5Mn0.4Co0.1O3在不同还原气氛下的电导率,在CH4和H2气氛中,La0.7Sr0.3Cr0.5Mn0.4Co0.1O3最大电导率分别达到了4.5和0.42 S·cm-1.
关键词:
钙钛矿
,
阳极
,
电导率
黄曼青
,
周全
,
刘峰
,
黄金角
材料导报
doi:10.11896/j.issn.1005-023X.2016.22.010
研究了0~1.4 T的直流磁场对陶瓷型铸造 Mg-Y-Cu-Zr 合金结晶取向和力学性能的影响。结果表明直流磁场对合金的初生相没有明显影响，但磁场强度大于1.12 T时，合金第二相的分布变得不连续。当磁场强度小于0.84 T时，α-Mg在(002)面的衍射峰逐渐增强，但变化不明显；当磁场强度大于0.84 T 时，α-Mg 基体在(002)、(101)面的衍射峰强度明显减弱，而在(100)晶面衍射峰强度有所增强。磁场处理后，合金的综合力学性能得到了改善；当磁场强度为1.4 T 时，其抗拉强度和伸长率最高，分别为237 MPa 和8.5%，较无磁场处理时分别提高了38.6%和33.4%。
关键词:
直流磁场
,
Mg-Y-Cu-Zr合金
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结晶取向
,
力学性能
Ying Liy Changzhen Wang Zhongli Zhang Jiangxin Wang
材料科学技术（英文）
The steel contains a small amount of hydrogen which will escape during the heat treatment. The hydrogen pressure in 16MnRE steel was investigated with a hydrogen sensor, which used SrCe0:95Yb0:05O3-α proton conductor as a solid electrolyte, YHx+YH2-z as a solid state reference electrode and Ni wire as electrode constructing a hydrogen concentration cell, shown as Ni|YHx+YH2-z |SrCe0:95Yb0:05O3-α |[H]steel |Ni. The response time of sensor is less than 10 s. The relational expression of hydrogen partial pressure with temperatures was determined using two shape proton conductors. The results showed the regularity in experimental temperature range, and the hydrogen partial pressure increased as its temperature was raised.
关键词:
Hydrogen sensor
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Proton conductor
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Solid electrolyte
