Phase transformations and crystallography of twins in martensite in Ti-Pd alloys

Minoru Nishida, Y. Morizono, H. Kijima, A. Ikeya, H. Iwashita, K. Hiraga

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Abstract

Phase transformations and crystallography of twins in near-equiatomic Ti-Pd alloys have been studied. In the first half we have found that the transformation temperature decreases with decreasing the Pd contents and the successive transformations take place in the Ti-rich alloys. While the transformation temperature is nearly constant with the composition and a single transformation takes place in the equiatomic and Pd-rich alloys. The solubility limit of TiPd compound in Ti-rich side is extended to about 55 at%Ti at 900 °C and abruptly decreased with decreasing temperature. In the latter half we have found three twinning modes, i.e., {111} Type I, 〈121〉 Type II and {101} compound twins, in the martensite. The {111} Type I and 〈121〉 Type II twinnings which are conjugate to each other coexist in the same variant. The {111} Type I twins are dominantly observed and the 〈121〉 Type II twins are less frequently observed. The former twinning is considered to be a lattice invariant shear. There is no martensite variant consisting wholly of the 〈121〉 Type II twins throughout the present observation. The 〈121〉 Type II twinning is considered to be a deformation twin due to the elastic interaction during the transformation. The {101} compound twinning is also considered to be a deformation twin, since the twin has an isolated fashion in the martensite variant. The boundary structure of the above three twinning modes was also discussed on the basis of lattice image.

Original languageEnglish
Pages (from-to)375-380
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Volume459
Publication statusPublished - 1997
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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