The Magnetic Behaviour of FeAl Alloys of B2‐Structure Investigated by Mössbauer Spectroscopy

Abstract

Abstract FeAl alloys in the concentration range 25 to 50 at% Al were investigated between 1.3 °K and room temperature by Mössbauer spectroscopy and magnetic measurements. These alloys are characterized by the simultaneous appearance of Fe atoms in two kinds of very different neighbourhood: 8 nn Fe and 4 or less nn Fe. This fact causes the appearance of strong fluctuation effects observed above 30 at% Al. At 33 at% Al two kinds of domains coexist, such which order magnetically above room temperature (“Fe 3 Al”) and other with a magnetic transition temperature of about 100 °K (“FeAl”). The concentration dependence of the observed hyperfine fields and the magnetic transition temperature is explained by the decrease of the iron magnetic moment with increasing Al‐content, which in this concentration range is not correlated to the number of next nearest neighbour Fe atoms but seems to be determined by the absolute Al‐content.