Rheological Transitions at Low Solid Fraction in Solidifying Magnesium Alloy AZ91
Transitions in the mechanical behaviour of solidifying alloys influence feeding mechanisms and defect formation during many casting processes. This paper explores dendrite coherency and the cracking transition during the equiaxed dendritic solidification of Mg alloy AZ91 using the continuous-torque technique and vane rheometry. The two techniques yielded similar dendrite coherency values of ~17% solid, and the cracking transition occurred at 40% solid in vane rheometry tests. These transition values are similar to those reported for Al alloys with equiaxed dendritic morphology and a similar grain size.
Young Won Chang, Nack J. Kim and Chong Soo Lee
C. M. Gourlay et al., "Rheological Transitions at Low Solid Fraction in Solidifying Magnesium Alloy AZ91", Materials Science Forum, Vols. 561-565, pp. 1067-1070, 2007