Thixoforming : Semi-solid Metal Processing

Figure 2.8 DICTRA-calculated composition profiles after
quenching with 50 K s 1 from 1418 C(fL ¼ 0.57). The dashed
vertical line shows the original solid–liquid interface before
quenching. The dashed horizontal lines show the C and Cr
contents before quenching [8].
equilibrium freezing range near termination of solidification, DT 88–98 , proposed by
Djurdjevic and Schmid-Fetzer [11]. A pronounced TFR may cause hot tearing and
should therefore be avoided. Since only single-phase alloys may develop a distinct
TFR, the applicability of SSM should be assessed also from this point of view. For
Mg–Al alloys, for example, it was shown that an increase in Al and Ca content might
Figure 2.9 Optical microscopy image of the intergranular region
of 100Cr6 (quenched from 1425 C; f L ¼ 0.57); martensite (M),
retained austenite (A), and manganese sulfides (MnS) along the
grain boundaries [8].
2.4 Proneness to Segregation and Hot Tearingj39