Quasi-in-situ observations of the sintering behaviour of molybdenum-alloyed sintered steels

The sintering behaviour of molybdenum pre-alloyed sintered steels was inves tigated. A scanning electron microscope with a hot stage attachment was use d, enabling quasi-in-situ observations of the sintering process. The materi al MSP 1.5Mo (Fe-1,5% Mo) sinters in the austenitic phase, while MSP 3.5Mo (Fe-3.5% Mo) sinters completely in the ferritic phase, due to the increased molybdenum mass content. The significantly higher self-diffusion coefficie nt of iron in the ferritic phase leads to the accelerated sintering of MSP 3.5Mo, compared to MSP 1.5Mo. The effect on the sintering behaviour by addi ng the alloying elements chromium and phosphorus was also studied. While ph osphorus accelerates sintering processes, chromium decreases the sintering rate. A pronounced shrinkage during non isothermal heating, due to cooperat ive particle movement, was detected for both sintered steels.