The Microstructure of a Magnetically Hard Zr2Co11 Alloy

Electron-microscopic and electron-graphic analysis has demonstrated that the Zr2Co11 compound has a complex structure. All grains consist of thin plates of a high-temperature rhombohedral phase, which are parallel to the (0001) crystallographic plane; the crystal lattices in the neighboring regions have a twin orientation relative to each other. The transformation of the rhombohedral phase into a low-temperature orthorhombic phase is accompanied by an additional splitting of these plates into regions in which the [001](orth) axes are parallel to the [0001](rhomb) axes, and the [010](orth) axes are rotated through an angle of about 120 degrees. These twin regions, alternating in the samples, favor the minimization of elastic stresses. In electron-diffraction patterns, there are also observed satellites, which testify the existence of structural incommensurate modulation in the [010] direction of the orthorhombic lattice with a period of modulation equal to 18-19 angstrom.