Microalloying Effects of Ca and Ni on High-Temperature Creep Behavior in Mg-Y-Zn Alloys
Microalloying Effects of Ca and Ni on High-Temperature Creep Behavior in Mg-Y-Zn Alloys
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DOI：
10.2320/matertrans.mc200722
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发表时间：
2008-05
影响因子：
1.2
通讯作者：
Mayumi Suzuki;K. Tsuchida;K. Maruyama
中科院分区：
文献类型：
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作者：
Mayumi Suzuki;K. Tsuchida;K. Maruyama
研究了含第四元素（Ni和Ca）的Mg-Y-Zn基合金的650 K高温蠕变强度和显微组织。0.5质量%钙的微合金化显着增加了Mg-3质量%Y-0.5质量%Zn合金中的层错密度。此外，钙的加入可以减小堆垛层错的尺寸。另一方面，在添加镍的合金中，形成许多沉淀物，并且估计的层错密度显著降低。Mg-Y-Zn-Ca合金的蠕变强度高于基础合金（Mg-3质量%Y-0.5质量%Zn，WZ 305）的蠕变强度。透射电子显微镜（TEM）观察表明，Mg-Y-Zn基合金在蠕变变形过程中，基体中基面上的大量α位错扩展。Mg-Y-Zn-Ni合金在蠕变前大量析出相的形成，导致基体中溶质原子的大量消耗和蠕变强度的降低。而Mg-Y-Zn-Ca合金中存在低的移动的位错密度和大的扩展α位错分离宽度，在650 K和20 MPa下表现出优异的蠕变强度。
High temperature creep strength at 650 K and microstructures of Mg-Y-Zn-based alloys with fourth elements (nickel and calcium) have been investigated. The microalloying of 0.5 mass% calcium markedly increases the stacking fault density in the Mg-3 mass%Y-0.5 mass%Zn alloy. Furthermore, the addition of calcium can decrease the size of stacking faults. On the other hand, in the nickel-added alloy, many precipitates were formed and the estimated stacking faults density decreased significantly. The creep strength of the Mg-Y-Zn-Ca alloy is higher than that of the base alloy (Mg-3 mass%Y-0.5 mass%Zn, WZ305). Transmission electron microscopic (TEM) observations revealed that many a-dislocations on the basal planes in the magnesium matrix are extended during creep deformation in Mg-Y-Zn-based alloys. There was significant consumption of solute atoms in the matrix and deterioration of creep strength in the Mg-Y-Zn-Ni alloy, because the formation of a large number of precipitates began before creep. On the other hand, both the low mobile dislocation density and the large separation width of extended a-dislocations were observed in the Mg-Y-Zn-Ca alloy, which exhibits excellent creep strength at 650 K under 20 MPa.