The effect of annealing on the transformation and the microstructure of Mn1 − xCrxCoGe alloys

• The annealing conditions determine the magnetostructural transition.
• A laminar microstructure along preferential planes observed by TEM
• A RSG to ferromagnetic transition at low temperatures is detected.

In this work the effect of different thermal treatments on the transformation behavior of Mn1 − xCrxCoGe alloys, with x = 0.15 and 0.20 has been analyzed. The changes in the transformation temperatures have been studied by differential scanning calorimetry (DSC). The results show that the structural transition temperature depends on the previous annealing. However, under the same heat treatment no significant change is observed on the transformation temperatures when replacing Mn by Cr. The microstructural evolution has been monitored using in-situ X-ray diffraction and transmission electron microscopy. The effect of an applied magnetic field on the transformation has been explored by SQUID magnetometry. Two different magnetic transitions are found: a first order paramagnetic (PM) to ferromagnetic (FM) corresponding to the transformation observed by calorimetry and a re-entrant spin glass to ferromagnetic transition.