Accession Number:

AD0669629

Title:

TRANSFORMATION PLASTICITY OF COBALT-NICKEL SINGLE CRYSTALS,

Descriptive Note:

Corporate Author:

ILLINOIS UNIV URBANA DEPT OF MINING METALLURGY AND PETROLEUM ENGINEERING

Personal Author(s):

Report Date:

1968-04-15

Pagination or Media Count:

58.0

Abstract:

The influence of an external stress on the allotropic transformation of single crystals of a Cobalt-30.5 Nickel alloy was investigated. Experimental results were obtained from dilatometry, x-ray diffraction, and optical and electron microscopy. The effects of stresses could be conveniently divided into three stress ranges. In range I, from 0 to about 400 gsq mm, the specimens exhibited on cooling a multivariant phase change and a considerable amount of retained cubic material. In range II, from 400 gsq mm to the elastic limit, the product phase had a simpler morphology. Single hexagonal regions grew in size and the cubic phase disappeared with increasing stress level. In range III, just above the elastic limit, specimens transformed into hexagonal single crystals. Specimens prestressed in range III and transformed in range I also became hexagonal single crystals. The observed macroscopic shear directions were mainly 112 on cooling but the behavior was more complicated on heating under stress. To explain these properties of the phase change, a model based on the nucleation of partial dislocations is proposed. Author

Subject Categories:

  • Physical Chemistry
  • Properties of Metals and Alloys
  • Crystallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE