Influence on the structural and magnetic properties of the pre-alloyed gas-atomized maraging steel powder during mechanical milling

Abstract

We investigated the influence on the structural and magnetic properties of gas-atomized maraging steel powder during mechanical milling. The as-received powder comprised, primarily, martensite phase (α) and traces of retained austenite (γ ); the saturation magnetization (MS ) and intrinsic coercivity (HCI ), at 300 K, were ~176 Am2 /kg and ~3 kA/m, respectively. Powders milled from 3 to 8 h comprised nanocrystalline α; the MS and HCI ranged from ~164 to 169 Am2 /kg and ~4.9 to 6.7 kA/m, respectively. Milling above 8 h formed austenite and extraneous intermetallic phases, reduced MS, and increased HCI. The MS increased with the decrease in the temperature from 300 to 60 K, for both the as-received and milled powders. The thermomagnetic behavior of the as-received and the milled powders from 300 to 900 K was fairly reversible. The magnetic properties of as-received and powder milled for 5 h were comparatively better than the powder milled for 56 h.