Semi-solid processing of engineering alloys by a twin-screw rheomoulding process

摘要

Based on the extensive experience in injection moulding of polymeric materials, a twin-screw rheomoulding process has been developed for semi-solid metal (SSM) processing of engineering alloys. In this process, a liquid alloy is fed into a twin-screw extruder, where the liquid alloy is sheared and cooled to a temperature between its liquidus and solidus to produce the desirable SSM slurry. The sheared semi-solid slurry is then transferred to a mould cavity for component shaping. The experimental results of rheomoulded alloys have demonstrated that, compared with other existing SSM processing techniques, the twin-screw rheomoulding process has many advantages, including production of fine and spherical solid particles distributed uniformly in the matrix, accurate control over a large range of solid volume fractions, easy operation, shorter cycle time and lower overall component cost.