Studies On Crytallization And Properties Of Melt-spun Quaternary Al-based Alloys

Rapidly solidified ribbons of the Al85Zr4Nb4Ni7 and Al85Y4Nd4X7 (X=Fe, Co, Ni) (at.%) alloys were produced by melt spinning(cooling rate 105-106k/s). The as-quenched and as-annealed microstructures of each rapidly solidified alloy ribbon wre investigated by using XRD, DSC, TEM etc. A 71 Vickers hardness tester measured the ambient-temperatures microhardness of the alloys annealed at different temperatures respectively. The measured region is near the chill surface of the ribbon. The thermal stability could be estimated indirectly by measuring the ambient-temperature microhardness after the isothermal annealing at different temperatures. The paper analyzed the influences about TM (transition metals) and Re(rare earth elements) on the microstructures and properties of the rapidly solidified Al85Zr4Nb4Ni7, Al85Y4Nd4Ni7, Al85Y4Nd4Fe7 and Al85Y4Nd4Co7 alloys.The study indicates that the additions of Fe, Co and Ni transition metals and Y, Nd rare earth elements are vital influence on the thermal stability and formation of amorphous structures of the melt-spun Al-Re-TM alloys, the additions of Fe, Co and Ni transition metals can improve the thermal stability of these alloys. The negative enthalpy of mixing between Al and Y, Nd elements is beneficial to the glass formation of Al-based alloys. The thermal stability of the amorphous alloys containing nannoscale Al particals is higher than those complete amorphous alloys. The article discuss the chemical short-range orders in those amorphous alloys influence on the glass formation of Al-based alloys. And explain crystallization behavior of the amorphous alloys introdued the crystallization mechanism of amorphous alloys predicted by Lu Ke et. al. It will provide the theoretical basis for the elevated temperature application of the quaternary Al-based alloys.