Teilkohärente Ausscheidungen in einer Eisen‐Chrom‐Kohlenstoff‐Legierung

Semicoherent precipitates in a Fe‐Cr‐C alloy Precipitation processes in ferromagnetic materials can be recorded very well by measuring the sensitive coercive field strength. It should be tested, whether also semicoherent precipitates have a sufficient clear interaction with Bloch‐walls. For this purpose the mild‐magnetic alloy X1FeCr25 served. To carry out the evidence sensitively, a method based on differences between H_C^t (heat‐treated state at T = 600…︁700°C) – H_C⁰ (quenched state from high temperature) = Δ H_C was used. A quantitative record of the amount of precipitates (as particle size) is possible by a decomposition parameter Δ H_C/Δ t. Plate‐like β′‐precipitates with planes {100}∥{100} in the α‐Fe solid solution have been proved by transmission electron microscopic investigations; this is the preparation state for the transition into the stable fcc phase M₂₃C₆. As a result, the quantitative electron microscopic proof of the β′‐phase can be supported by magnetic measurements, qualitatively and quantitatively. The estimated values of the activation energy for the process in the 1st maximum of precipitation in X1FeCr25 are higher than for the stable phases as the orthorhombic M₃C or the cubic complex M₆C in other steels and give a hint to the difficult processes related to nucleation as to the transition into M₂₃C₆.