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采用金属型铸造和慢速凝固,在不同冷却速率下制备了Mg-10Gd-3Y-1.8Zn-0.5Zr(质量分数,%)(GWZ1032K)合金.采用SEM,TEM和XRD研究了冷却速率不同的GWZ1032K合金的组织和相构成.在GWZ1032K合金中,α-Mg基体中的层片状14H-LPSO结构随着冷却速率的下降而增加,在冷却速率为0.005℃/s的试样中充满了整个晶粒;随着合金冷却速率降低,GWZ1032K合金中晶界第二相分别由5℃/s时的(Mg,Zn)_3RE相转变为0.5和0.1℃/s时的(Mg,Zn)_3RE相和14H-LPSO结构的χ相共存;在0.01和0.005℃/s时只有14H-LPSO结构的χ相.结果显示在接近于平衡凝固的缓慢冷速条件下,更容易形成具有稳定结构的层片状14H-LPSO结构和χ相.在冷却速率为0.5和0.1℃/s时,(Mg,Zn)_3RE共晶相和χ相共存,(Mg,Zn)_3RE共晶相和χ相的位向关系为[110]_(χphase)∥[(?)23]_((Mg,Zn)_3RE)和∠g(001)_(χphase)g(110)_((Mg,Zn)_3RE)=8.4°.
The alloy Mg-10Gd-3Y-1.8Zn-0.5Zr (mass fraction,%) (GWZ1032K) was prepared by metal casting and slow solidification at different cooling rates.The effects of different cooling rates were studied by SEM, TEM and XRD GWZ1032K alloy.In the GWZ1032K alloy, the lamellar 14H-LPSO structure in α-Mg matrix increases with the decrease of the cooling rate, and the sample with the cooling rate of 0.005 ℃ / s is filled with the whole (Mg, Zn) 3 RE phase at 5 ℃ / s to (Mg, Zn) 3 RE phase at 0.5 ℃ and 0.1 ℃ / s, respectively. With the decrease of alloy cooling rate, And the χ phase of 14H-LPSO structure coexist and only the χ phase of 14H-LPSO structure at 0.01 and 0.005 ℃ / s.The results show that under the condition of slow cooling rate close to equilibrium solidification, it is easier to form a layer with stable structure (Mg, Zn) 3 RE eutectic and x phase, (Mg, Zn) 3 RE eutectic and x phase at the cooling rate of 0.5 and 0.1 ℃ / s The relationship is [110] _ (χphase) ∥ [(?) 23] _ ((Mg, Zn) _3RE) and ∠g (001) _ (χphase) g °.