Analysis of fine strain field around precipitates using a HOLZ pattern

Yoshito Takemoto, Masahiro Nagae, Moritaka Hida, Akira Sakakibara, Jun Takada

Research output: Contribution to journalArticlepeer-review

Abstract

Fine strain fields around TiN precipitates in Mo alloys, were analyzed by a newly proposed HOLZ (High Order Laue Zone) pattern method, using transmission electron microscopy. The shape of the TiN precipitates changed into three different types after heat treatment thin plate, rod and sphere. The thin foils for TEM observation were prepared by an electro-polish method. It was found in preliminary experiments using pure Mo that the appropriate condition to obtain a good HOLZ pattern for bcc materials was to choose an orientation which satisfied both low density and uniform distribution of reciprocal spots within the zero order Laue zone. The HOLZ patterns were therefore acquired from the [410] direction of the matrix at room temperature using a convergent electron probe 8.8 nm in diameter operated at 200 kV. Many HOLZ patterns were taken by shooting the electron probe within 150 nm×150 nm areas that included a precipitate. These patterns were imported into a personal computer using a scanner. It was found that the HOLZ patterns hardly changed its configuration with position but moved as a whole within the center disk depending on position, suggesting lattice rotation of the matrix. The vector maps which indicated the degree and direction of lattice rotation around a precipitate were produced for three types of precipitates. The thin plate of TiN generated a symmetrical mountainous strain field. The rod yielded an asymmetrical valley strain field, and the sphere hardly influenced the matrix. It is considered that the difference in the form of the strain field depending on the shape of precipitate was caused by the degree of coherency between the matrix and the precipitates.

Original languageEnglish
Pages (from-to)283-286
Number of pages4
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume64
Issue number5
DOIs
Publication statusPublished - Jan 1 2000

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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