MICROSTRUCTURE OF Mg-Zn-Zr-Y ALLOYS
摘要
In the as-cast Mg-Zn-Zr-Y alloys, the quasicrystal phases show massive and eutectoid plate morphologies. The selected area dijfraction(SAD) revealed that a large pan of the quasicrystals are face-centered icosahedral (FCI), while a small amout of the quasicrystals belong to the simple icosahedral (SI) phase. It was found that in homogenized alloys, a part of the grain boundry phases was dissolved,and small massive W-phase and lath-shape MgZn_(2) phase dispersedly precipitate in the grains. The transformation of the quasicrystals relates to the temperature. After homogenizing at 360 ℃ , the quasicrystals still present, while after homogenizing at 400 ℃ , the quasicrystals transformed into a new C-type orthorhombic phase witha = 0.975 nm, b = 1.137nm and=0.935 nm.