LU Feng CAO Fengyu LI Chengji University of Science and Technology Beijing
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Beijing
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ChinaZHANG Yongxiang CHEN Yonggang Beijing Institute of Machine Tools
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Beijing
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China Faculty of Metallograph
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University of Science and technology Beijing
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Beijing 100083
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China
金属学报(英文版)
Effect of Ca on hardenability and CCT diagram of steel 58CrV has been investigated by means of end-quenching and thermal expansion.An addition of 0.006 wt-%Ca to the steel may improve the hardenability,reduce the critical cooling rate of transformation of pearlite or bainite under continuous cooling and increase the M_s.AES analysis showed that Ca segre- gates markedly along austenitie grain boundaries,and accelecrates the segregation of C,Cr and Si.It is believed that besides towards deoxidizing and desulphurizing as well as improving sulphide morphology,a trace of Ca in steel 58CrV behaves towards microalloying.
关键词:
Ca
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null
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null
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null
QIAO Lijie LIU Rui XIAO Jimei University of Science and Technology Beijing
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Beijing
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China
金属学报(英文版)
The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.
关键词:
stress corrosion cracking
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null
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null
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null
孙丹丹
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潘尚可
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任国浩
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吴云涛
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商珊珊
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张国庆
无机材料学报
doi:10.3724/SP.J.1077.2013.12735
针对Ce:Li6Lu(BO3)3晶体有效原子序数(zeff)高的问题,采用低原子序数的Y3+离子部分置换晶体中的Lu3+离子.通过固相合成法制备了Ce:Li6Lu1-xYx(BO3)3(0≤x≤1)固溶体.X射线粉末衍射(XRD)分析表明,该系列固溶体结构与Li6Gd(BO3)3晶体相同,空间群为P21/c.其X射线激发发射(XSL)的发光强度随着Y3+的含量增加而降低,当x=0.5时,固溶体的有效原子序数与Li6Gd(BO3)3闪烁体相当,但XSL发光强度是其1.4倍.Ce:Li6Lu0.5Y0.5(BO3)3的XSL光谱和PL光谱都在400 nm附近出现Ce3+离子的特征峰,可拟合出361和419 nm两个发光分量,分别对应于Ce3+离子的激发态电子的5d1→2F5/2和5d1→2F7/2能级跃迁.Ce:Li6Lu0.5Y0.5(BO3)3固溶体的衰减时间比Ce:Li6Lu(BO3)3略长,为19.6 ns.当x=0.50～0.70时,Ce:Li6Lu1-xYx(BO3)3(0≤x≤1)闪烁体比较适合作为中子探测材料.
关键词:
固相合成
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Ce∶Li6LU1-xYx(BO3)3
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X射线激发发射谱
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PL光谱
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衰减时间
刘玮
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潘尚可
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李焕英
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蒋勇
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陈晓峰
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任国浩
无机材料学报
doi:10.15541/jim20150080
为了提高中子探测效率,以富集10B的H310BO3为原料,通过提拉法生长了富集10B的Ce：Li6Lu(10BO3)3晶体。X射线激发发射光谱测试表明：其发光峰位于360~480 nm,属于Ce3+离子典型的5d -4f跃迁发光,其闪烁发光效率为BGO晶体的3.9倍。在350 nm紫外光和137Cs所发出的662 keV的γ射线激发下测得的衰减时间分别为21.0 ns和31.7 ns,在137Cs辐射源激发下所测得的相对光输出是CsI(Tl)晶体的20%,能量分辨率为9.7%。在慢化252Cf中子源激发下可以观测到明显的中子全能峰,其能量分辨率为33%。上述研究结果表明, Ce：Li6Lu(10BO3)3晶体具有较高的闪烁效率、快的衰减时间和良好的中子探测效率,是一种具有应用前景的中子探测用闪烁晶体。
关键词:
Ce:Li6Lu(10BO3)3晶体
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中子探测
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提拉法
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闪烁晶体
