The Influence of Vanadium Addition on Fracture Behavior and Martensite Substructure in a Ni-36.5at.%Al Alloy

Ni-36.5at.%Al 합금에서 V 첨가가 파괴거동 및 마르텐사이트 내부조직에 미치는 영향

  • Kim, Young Do (Special Alloy Research Lab. Korea Institute of Science & Technology) ;
  • Choi, Ju (Special Alloy Research Lab. Korea Institute of Science & Technology) ;
  • Wayman, C. Marvin (Department of Materials Science and Engineering, University of lIlinois at Urbana-Champaign)
  • 김영도 (한국과학기술연구원 특수강연구실) ;
  • 최주 (한국과학기술연구원 특수강연구실) ;
  • Received : 1992.04.08
  • Published : 1992.06.25

Abstract

Fracture behavior and martensite substructure of Ni-36.5at.%Al alloy were investigated with the addition of vanadium which is known as scavenging element of grain boundary. The fracture surfaces were examined by scanning electron microscopy and the EDX spectrometer was applied for composition analysis of fracture surfaces. The substructure of martensite was studied by transmission electron microscopy. By addition of vanadium, fracture surfaces show mixed modes of intergranular and transgranular fracture and more Al content is found on the grain boundaries. For Ni-36.5at.%Al alloy, the planar faults observed in the martensite plates are the internal twins. By increasing the vanadium content, the modulated structure with stacking faults and dislocations dominates while the twinned martensite disappears. The stacking fault is determined to be extrinsic due to the substitution of V for Al. It is concluded that the segregation of sulfur on the high-energy state stacking fault area suppresses the intergranular fracture.