微量Sc对7085铝合金淬火敏感性的影响

采用末端淬火实验、光学显微镜、差热分析、能谱仪和透射电镜研究微量Sc对7085铝合金淬火敏感性的影响。结果表明:在7085铝合金中添加Sc会提高该合金的淬火敏感性。添加Sc后,会在基体中形成弥散分布的Al3(Sc,Zr)粒子,该粒子能够稳定亚晶,强烈抑制再结晶,增加晶界数量;在淬火过程中,随着冷却速度的降低,粗大的平衡η相以Al3(Sc,Zr)粒子为异质形核核心析出,同时也在亚晶界上大量析出长大;η相的析出,降低了基体固溶体的过饱和度,提高了合金的淬火敏感性。

Microstructure and mechanical properties of Al-5.8Mg-Mn-Sc-Zr alloy after annealing treatment

An A1-5.8Mg-0.4Mn-0.35（Sc＋Zr） （mass fraction, %） alloy sheet was prepared using water chilling copper mould ingot metallurgy processing which was protected by active flux. The influence of stabilizing annealing on mechanical properties and microstructure of the cold rolling sheet was studied. The results show that the strength and hardness of the alloy decrease, while the elongation increases with increasing the stabilizing annealing temperature. With the increase of stabilizing annealing time, the strength and hardness of the alloy drop slightly but its ductility exhibits no change. Partial recovery and recrystallization orderly occur with the increase of annealing temperature during stabilizing treatment. Only different degrees of recovery occur in the alloys annealed below 400 ℃ for 1 h. Partial recrystallization occurs after annealed at 450 ℃ for 1 h. By annealing at 300 ℃ for 1 h, the alloy can obtain the optimum application values of δb, δ0.2 and δ, which are 436 MPa, 327 MPa and 16.7%, respectively.

微量Sc对5A01铝合金性能与显微组织的影响

研究了在5A01铝合金基础上添加0.2％Sc和0.3％Sc后合金的显微组织、力学性能、腐蚀性能及焊接性能。结果表明,微量Sc的加入,初生Al_3Sc或Al_3(Sc,Zr)粒子可成为有效的非均质晶核,大大地细化合金的铸态晶粒,次生Al_3Sc或从Al_3(Sc,Zr)粒子能有效地钉扎位错和亚晶界,稳定亚结构并强烈抑制合金的再结晶。因此,加入Sc后的试验合金基体及焊接强度提高,腐蚀性能和焊接性能与5A01铝合金相当,甚至更好。

Sc含量对Al-Mg-Sc-Zr合金铸态组织及时效强化的影响

用金相显微镜（OM）、扫描电镜（SEM）、透射电镜（TEM）及显微硬度仪研究了Sc含量对Al—5．5Mg．0．5Mn-XSc-0．1Zr（质量分数，％）（0．05≤x≤0．50）合金铸态显微组织和时效处理后二次析出相的形貌及其强化作用的影响。结果表明：当Sc含量少于0．09％（质量分数，下同）时，凝固过程中无含Sc相析出，铸锭组织为柱状树枝晶，时效后强化作用有限；当Sc含量在0．16％～0．23％时，凝固过程中析出少量初生及共晶A13（So，Zr）相，这既能够细化晶粒，又不影响时效后二次析出相的热稳定性，时效后合金的硬度也较高；而Sc含量过高（Ⅳ≥0．23）时，合金中初生和共晶A1s（So，Zr）相的含量增多，虽然也能够细化晶粒，但凝固后基体中固溶的Zr含量也会随之降低，导致二次A13（So，Zr）相的热稳定性降低，450℃时效24h后二次析出相粗化严重，强化作用很弱。