Study On Solidification Processing Of AZ61Magnesium Alloy By Elf-inoculation Method

The preparation of semi-solid slurry/billet is a key step of semi-solid formingtechnique; the crucial procedure is the production of semi-solid slurry with small andspherical primary particles uniformly suspended in liquid phase. In this thesis, a noveltechnology of high efficiency was developed known as Self-Inoculation Method (SIM)with melt and melt mixing, and the evolution mechanism of the slurry withnon-dendrite structure was studied from solidification and grain growth points of view.Accordingly, the effect of processing parameters on microstructure of the final slurrywas systematically discussed, contrasting other methods, such as traditional casting,slope cooling plate, liquid-liquid mix method and so on.The results show that:1. The quality of semi-solid slurry (primary grain diameter of48μm-52μm) isdetermined by pouring temperature and slop angle of fluid director. The optimumparameters to prepare semi-solid slurry of AZ61alloy are slop angle in30～45O, melttreatment temperature at635～695℃；2The operation temperature range of SIM method to prepare AZ61alloy is about60℃, which obviously improves the melt fluidity, and contributes to fabrication ofcomplex components；3. The intense turbulent of mixing melts is introduced in SIM method. The lowsuperheat pouring, local chill of fluid director, washing action, and mixing actionimprove the heterogeneous nucleation, and promote refinement of primary grain.