title: Structure investigations of ferromagnetic Co-Ni-Al alloys obtained by powder metallurgy.
abstract: Elemental powders of Co, Ni and Al in the proper amounts to obtain Co(35)Ni(40)Al(25) and Co(40)Ni(35)Al(25) nominal compositions were ball milled in a high-energy mill for 80 h. After 40 h of milling, the formation of a Co (Ni, Al) solid solution with f.c.c. structure was verified by a change of the original lattice parameter and crystallite size. Analytical transmission electron microscopy observations and X-ray diffraction measurements of the final Co (Ni, Al) solid solution showed that the crystallite size scattered from 4 to 8 nm and lattice parameter a = 0.36086 nm. The chemical EDS point analysis of the milled powder particles allowed the calculation of the e/a ratio and revealed a high degree of chemical homogeneity of the powders. Hot pressing in vacuum of the milled powders resulted in obtaining compacts with a density of about 70% of the theoretical one. An additional heat treatment increased the density and induced the martensitic transformation in a parent phase. Selected area diffraction patterns and dark field images obtained from the heat-treated sample revealed small grains around 300 nm in diameter consisting mainly of the ordered gamma phase (gamma'), often appearing as twins, and a small amount of the L1(0) ordered martensite.
authors.affiliation: Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Cracow, Poland. nmmaziar@imim-pan.krakow.pl
authors.forename: W
authors.initials: W
authors.lastname: Maziarz
authors.forename: J
authors.initials: J
authors.lastname: Dutkiewicz
authors.forename: L
authors.initials: L
authors.lastname: Lityńska-Dobrzyńska
authors.forename: R
authors.initials: R
authors.lastname: Santamarta
authors.forename: E
authors.initials: E
authors.lastname: Cesari