Anomalous Effect of Pressure on the Curie Temperature in Mechanically Alloyed Fe-Ni Invar

Measurements of magnetic susceptibility in mechanically alloyed Fe-Ni Invar alloys were taken under pressures up to 7.5GPa. The rate of decrease in the Curie temperature for 700°C annealed specimen was larger than that annealed at 1000°C. This result can be explained by considering the fact that the width of the concentration fluctuation becomes larger in the specimen annealed at lower temperature.