Papers by Keyword: Solid Phase Transformation

Abstract: During Thixomolding process, solid phase fraction decreased with the injection velocity increasing. Meanwhile, the solid phase morphology changed from irregular dendrite to near spherical. Friction heat produced by high speed melt flow could cause partial melt of solid phase, and the morphology of solid phase would form into globular. The dendritic solid phase can be broken by high speed melt flow under the condition of injection velocity higher than 2.0m/s.

Abstract: An original approach based on semi-automatic treatment of Kikuchi patterns collected by Transmission Electron Microscopy is used to analyse the a2 an g variant distributions in a quaternary TiAl-based alloy (Ti-48at.%Al-2%Cr-2%Nb), with two lamellar microstructures of different fineness. Statistic data analysis shows that neither g variant orientations nor interface misorientations are randomly distributed within a given grain. The largest deviation from randomness is observed for the coarser microstructure. We also pointed out the presence of g|g subboundaries between same but slightly misoriented variants, as well as the existence of some semicoherent g|g twins accommodated by dislocation lattices. The analysis of the misorientation distributions of g|g and g|a2|g interfaces suggests that a variant selection occurs during growth and coarsening stages of the a ® a2 + g transformation process.