TRANSFORMATION PLASTICITY OF COBALT-NICKEL SINGLE CRYSTALS,
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 g/sq mm, the specimens exhibited on cooling a multivariant phase change and a considerable amount of retained cubic material. In range II, from 400 g/sq 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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 15, 1968
- Accession Number
- AD0669629
Entities
People
- Carl Altstetter
- Emmanuel Delamotte
Organizations
- University of Illinois Urbana–Champaign