人工时效前的室温停留,会对7475铝合金的人工时效产生一定的影响.通过电导率的测量,说明自然时效时由于GP区的弥散析出,导致样品的电导率持续下降;长时间室温停留后再进行人工时效时,由于GP区的形成,夺取一部分空位,使溶质原子扩散的驱动力减小,析出反应的表观激活能变大,电导率始终低于淬火后直接进行人工时效的样品.通过JMAK方程处理了所得数据,计算出重要的时效动力学参数t_C和n,并说明了各自的影响因素.
The effect of delaying at room temperature after quenching on artificial aging of 7475Al alloy was studied by electrical conductivity measurements. During room temperature aging,the GP zones in the alloy precipitate dispersively,and its electrical conductivity decreases. Because of the decrease of vacancy concentration,the alloy after long-term delaying at room temperature presents a higher apparent activation energy for the precipitation. and the electrical conductivity of the alloy naturally aged is lower than that of in-quenched alloy. The data of experiments are fitted by JMAK equation,and the parameters of t_C and n in the equation is deduced and the factors influencing the values of t_C and n is discussed.
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