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A MICROMECHANISM FOR B IMPROVING THE MECHANICAL PROPERTIES OF MONO- AND POLYCRYSTALLINE Ni3Al ALLOYS

DENG WEN XIONG LIANG-YUE LONG QI-WEI WANG SHU-HE GUO JIAN-TING

A MICROMECHANISM FOR B IMPROVING THE MECHANICAL PROPERTIES OF MONO- AND POLYCRYSTALLINE Ni3Al ALLOYS

DENG WEN, XIONG LIANG-YUE, LONG QI-WEI, WANG SHU-HE, GUO JIAN-TING
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  • The microdefects and electronic structure have been studied by measuring the positron lifetime spectra of mono- and polycrystalline Ni3Al alloys with B content ranging from 0.00 to 2.22at%,The experimental results show that the opening space of the defect on grain boundary is larger than that of a monovacancy in polycry-stalline Ni3Al alloy. More valence electrons participate in Ni-Ni and Ni-Al bondings in bulk corresponding to stronger cohesion, while less valence electrons parti-cipate in those on grain boundaries corresponding to weaker cohesion. When B atoms segregate to defects, they form strong covalent bondings with Ni and A1 atoms and strengthen the bonding cohesion in those locations. The interaction of B atoms which occupy interstitial sites,with Ni and Al atoms in bulk leads to the increase of the density of valence electrons, thus increases the bonding cohesion in the bulk.
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  • Received Date:  08 June 1992
  • Accepted Date:  16 November 1992
  • Published Online:  20 January 1994

A MICROMECHANISM FOR B IMPROVING THE MECHANICAL PROPERTIES OF MONO- AND POLYCRYSTALLINE Ni3Al ALLOYS

  • 1. (1)中国科学院国际材料物理中心,中国科学院金属研究所; (2)中国科学院金属研究所

Abstract: The microdefects and electronic structure have been studied by measuring the positron lifetime spectra of mono- and polycrystalline Ni3Al alloys with B content ranging from 0.00 to 2.22at%,The experimental results show that the opening space of the defect on grain boundary is larger than that of a monovacancy in polycry-stalline Ni3Al alloy. More valence electrons participate in Ni-Ni and Ni-Al bondings in bulk corresponding to stronger cohesion, while less valence electrons parti-cipate in those on grain boundaries corresponding to weaker cohesion. When B atoms segregate to defects, they form strong covalent bondings with Ni and A1 atoms and strengthen the bonding cohesion in those locations. The interaction of B atoms which occupy interstitial sites,with Ni and Al atoms in bulk leads to the increase of the density of valence electrons, thus increases the bonding cohesion in the bulk.

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