【摘要】 采用DSC、金相、扫描电镜及能谱分析、X射线衍射相分析等方法,研究了7050合金Φ200mm半连续铸锭的结晶相及其在470℃均匀化处理过程的变化规律。结果表明:7050合金半连续铸锭中存在大量非平衡凝固共晶体,其过烧温度为477℃,共晶体中的非基体共晶相为MgZn2型晶体结构的含AlZnMgCu元素的非平衡第二相;在均匀化处理过程中,该非平衡凝固共晶体不仅向合金基体溶解还转变成Al2CuMg(S相),S相在该合金中的熔化温度为490℃左右;在470℃均匀化处理时,半连续铸锭中含Zn结晶相于12h前全部消失,其中部分形成S相,但在470℃均匀化处理时,S相不能完全溶入合金基体。铸锭中还存在少量的块状Al7Cu2Fe相,该相在均匀化处理过程中基本保持不变。更多还原

【Abstract】 The constituent of the Φ 201 mm semicontinuous casting ingot of 7050 aluminum alloy and their evolution during homogenizing treatment at 470 ℃ were studied by means of differential scanning calorimeter(DSC), optical microscope(OM), scanning electron microscope with energy dispersive X-ray spectroscopy(SEM-EDS) and X-ray diffraction(XRD) analysis. The results showed that semicontinuous casting ingot of 7050 aluminum alloy included a large number of nonequilibrium eutectic whose overheating temperature was 477 ℃, a nonequilibrium second phase which contained AlZnMgCu with the crystal structure of MgZn2 in the eutectic. During homogenizing treatment, nonequilibrium eutectic not only dissolved into the matrix, but also transforms to Al2CuMg(S phase) which was melted at 490 ℃ in this alloy. When homogenizing at 470 ℃, Zn element in the second phase of the nonequilibrium eutectic dissolved into its matrix completely before homogenizing treatment for 12 h, and some of Zn phases transformed to Al2CuMg (S phase). However, S phase did not dissolve completely into the matrix alloy when homogenized at 470 ℃. In the alloy ingot there were a few block Al7Cu2Fe phases in, which changed a little after homogenizing treatment.更多还原