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本文利用硬度,光学显微镜和透射电镜研究了微量Mn(0.48wt-%)对Al-5.0Zn-1.8Mg合金的沉淀过程,临界形核温度(T_C~′)和显微组织参数的影响,并与Cr和Cu的作用特点进行了比较.实验结果表明,Mn能细化晶粒和提高HV,但没有强烈的抑制再结晶和提高T_c~′的作用.在选用的时效条件下(120—200℃),含Mn合金的PFZ比无Mn合金窄,HV比无Mn合金高.在时效初期或进行低温时效(T_a≤160℃),Mn能促进晶界沉淀相(GBP)和基体沉淀相(MPt)的长大,但在时效后期或进行高温时效(Ta≥180℃),Mn又能抑制它们长大,有明显的稳定化作用.Mn对显微组织参数的这种影响与Cr和Cu的影响不同,可用Mn原子集团参与了GP区形核和含Mn之GP区的吞并长大速度慢的观点来说明.
In this paper, the influence of trace Mn (0.48 wt-%) on the precipitation process, the critical nucleation temperature (T_C ~ ’) and the microstructure parameters of Al-5.0Zn-1.8Mg alloy was investigated by hardness, optical microscope and transmission electron microscope And the characteristics of Cr and Cu were compared.The experimental results show that Mn can refine the grain and improve the HV, but there is no strong inhibition of recrystallization and improve the T_c ~ ’role in the selected aging conditions (120-200 ℃). The PFZ containing Mn alloy is narrower than the non-Mn alloy and the HV is higher than the non-Mn alloy.Mn can promote the intergranular precipitation phase (GBP) and the matrix precipitation phase (T_a≤160 ℃) during the initial aging or low temperature aging MPt) growth, but in the late aging or high temperature aging (Ta ≥ 180 ℃), Mn can inhibit their growth, significant stabilizing effect.Mn on the microstructure parameters of this effect with Cr and Cu The effect of different, available Mn atoms involved in the GP zone nucleation and Mn-containing GP area annexation grow up slow to illustrate.