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采用金相显微镜、扫描电镜、X射线衍射仪和万能试验机等分析了冷却速度(0.11、0.29、14.93℃/s)对Al-13Si-4Cu-1Mg-2Ni合金显微组织、相组成和力学性能的影响。结果表明:合金凝固期间形成的强化相主要包括共晶硅、M-Mg_2Si相、γ-Al_7Cu_4Ni相、δ-Al_3CuNi相、ε-Al_3Ni相、Q-Al_5Cu_2Mg_8Si_6相等。随着冷却速度的提高(0.11~14.93℃/s),合金晶粒尺寸由81.4μm减小到30.4μm,ε-Al_3Ni相消失,Q-Al_5Cu_2Mg_8Si_6相出现,白色δ相和γ相由尺寸很大的网状、团簇状变成了尺寸较小的网状、汉字状。铸锭铸态力学性能明显提高,硬度由0.11℃/s时的80.9 HB提高到14.93℃/s时的125.7 HB,抗拉强度由189.3 MPa提高到282.5 MPa,断后伸长率由1.6%提高到2.8%。
The microstructure, phase composition and mechanical properties of Al-13Si-4Cu-1Mg-2Ni alloy were analyzed by metallographic microscope, scanning electron microscopy, X-ray diffraction and universal testing machine at different cooling rates (0.11,0.29 and 14.93 ℃ / s) The impact of performance. The results show that the strengthening phases formed during solidification of the alloy mainly consist of eutectic silicon, M-Mg 2 Si phase, γ-Al 7 Cu 4 Ni phase, δ-Al 3 CuNi phase, ε-Al 3 Ni phase and Q-Al 5 Cu 2 Mg 8 Si 6. With the increase of the cooling rate (0.11-14.93 ℃ / s), the grain size of the alloy decreases from 81.4μm to 30.4μm, the ε-Al_3Ni phase disappears and the Q_Al_5Cu_2Mg_8Si_6 phase appears. The white δ and γ phases are large in size Of the mesh, cluster into a smaller mesh, Chinese shape. The as-cast mechanical properties of the ingot were significantly improved. The hardness increased from 80.9 HB at 0.11 ℃ / s to 125.7 HB at 14.93 ℃ / s, and the tensile strength increased from 189.3 MPa to 282.5 MPa. The elongation at break increased from 1.6% 2.8%.