(1. 上海交通大学材料科学与工程学院,上海 200240;
2. 上海交通大学金属基复合材料国家重点实验室,上海 200240;
3. 上海市先进高温材料及其精密成形重点实验室,上海 200240)
摘 要: 采用透射电镜、扫描电镜、三维原子探针等手段研究Al-Zr-Y合金的时效析出行为及Y含量对合金性能的影响规律。结果表明:Al-Zr-Y合金时效初期首先析出Al3Y相,可能成为Al3Zr时效析出的异质核心;长时间时效后,Y有向析出相和基体界面处偏聚的倾向,最终形成无核壳结构的Al3(Zr,Y)复合析出相;在三元Al-Zr-Y合金中,由于Zr的存在,Y在α(Al)中的平衡固溶度大幅度下降,600 ℃下的平衡固溶度从0.13%(质量分数)降至0.03%。Y含量较高的Al-0.30Zr-0.08Y在凝固及冷却过程中,过饱和的Y转变为沿晶界分布的Al3Y共晶和晶内一次析出微米级Al3Y颗粒,使铝基体中的有效Y含量较Al-0.30Zr-0.03Y中的降低4倍。Al-0.30Zr-0.03Y合金在时效过程中表现出更高的形核密度、更小的析出相尺寸和更优的抗粗化能力,合金的抗再结晶温度达到500 ℃,比Al-0.3Zr和Al-0.30Zr-0.08Y合金的抗再结晶温度分别高出125和75 ℃。
关键字: Al3(Zr,Y);析出机制;形核密度;抗粗化;抗再结晶
(1. School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China;
2. State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China;
3. Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, Shanghai 200240, China)
Abstract:The aging process of Al-Zr-Y and the effect of Y on the properties of alloy were studied by transmission electron microscopy, scanning electron microscopy and three dimensional atom probe. The results show that,the Al3Y precipitates form as the heterogeneous core at early aging stage of Al-Zr-Y alloy, which accelerates the diffusion and precipitation of Zr, Y has the tendency to cluster in the precipitate and matrix interface after long-time aging. Finally, Al3(Zr,Y) composite precipitates without core-shell structure forms in the alloy. The solubility of Y inα(Al) decreases from 0.13% to 0.03% (mass fraction) after aging at 600 ℃ for 50 h because of Zr. During solidification of Al-0.3Zr-0.08Y, supersaturated Y produces eutectic Al3Y along the grain boundaries and micron level Al3Yin the grain, which makes the content of Y in the matrix is 4 times lower than that of Al-0.30Zr-0.03Y. Al-0.30Zr-0.03Y shows higher nucleation density, smaller precipitate radius and slower coarsening rate. The recrystallization temperature of Al-0.30Zr-0.03Y reaches 500 ℃, which is 125 and 75 ℃ higher than those of Al-0.3Zr and Al-0.3Zr-0.08Y, respectively.
Key words: Al3(Zr,Y); precipitation mechanism; nucleation density; coarsening resistance; recrystallization resistance