【作者】 郝文博；

【导师】 邓文；

【作者基本信息】 广西大学 ， 材料物理与化学， 2006， 硕士

【摘要】 本文采用双探头符合技术，大幅度地降低正电子湮没辐射多普勒展宽谱的本底，谱线高能端峰高与本底之比大于1.5×10⁴，可分析正电子与原子内层电子湮没对谱线的贡献。利用正电子湮没辐射多普勒展宽装置研究了Ni—Cr—Co合金和铝化物金属间化合物合金中的3d电子行为，讨论3d电子对合金力学性能的影响。 测量Ni、Cr、Co金属以及不同配比Ni-Cr-Co合金的多普勒展宽谱，从中提取3d电子的信息。纯元素Cr，Co和Ni商谱的峰形取决于正电子与3d电子的湮没概率，随着Cr、Co、Ni的3d电子（5，7和8）数目的增加，峰位往高动量移动，峰值也更高。在Ni-Cr-Co合金中，原子间主要以金属键结合，从而使Ni-Cr-Co合金具有良好的延展性。 测量Zr、Nb、Ni、Al金属以及NiAl，Ni₅₀Al₄₈Zr₂和Ni₅₀Al₄₈Nb₂合金的多普勒展宽谱，可从中提取出3d电子的信息。在NiAl合金中，正电子与3d电子湮没的概率较低，这说明Ni的部分3d电子与Al原子的3p电子被局域化形成强共价键，从而减少了正电子与Ni的3d电子湮没的概率。在NiAl合金中加入少量Zr和Nb原子，将抑制Ni d-Al p成键趋势，提高d-d电子对相互作用，从而增加了正电子与d电子湮没的概率。Ni₅₀Al₄₈Nb₂合金商谱的d电子信号高于Ni₅₀Al₄₈Zr₂商谱，即加入Nb比加入Zr对提高NiAl合金中d—d电子对相互作用元素更有效。 测量Sn、Nb、Ti、Al金属以及TiAl，Ti₅₀Al₄₈Nb₂和Ti₅₀Al₄₈Sn₂的多更多还原

【Abstract】 The behavior of 3d electron and its effect on the properties of alluminide intermetallic compound and Ni-Cr-Co alloys have been studied by using the Doppler broadening of positron annihilation radiation technique. The Doppler broadening spetra were measured by two-detector coincidence system, and the background of the spectrum can be reduced remarkably, with a peak to blackground ratio of about 1.5 ×10~4, which allows obtaining the contribution of annihilations with core electrons.The 3d electron signal for the transition metals (Ni, Cr, Co) and the Ni-Cr-Co alloys with different Co content can be extracted from Doppler broadening spectra of positron annihilation radiation. The detailed shape of the high-momentum part of the Doppler spectrum depends on the probability of the positron annihilation with the 3d electrons of the atom. In the case of the ratio curves of Ni, Cr, Co metals, with the increase of the 3d electrons (Cr, 5; Co, 7; Ni, 8), the peak position of ratio curve moves toward higher momentum, and the heigh of the peak increases. The bonding nature in Ni-Cr-Co alloys is metallic, and the Ni-Cr-Co alloys shown good ductility.更多还原