LY12cz铝合金晶间腐蚀模拟试验研究

用金属间化合物 θ(CuAl₂)、S(Al₂CuMg)、MnAl₆与纯Al(L1)组成多电极体系,以模拟LY12cz合金的晶界区.通过电化学测试、SEM和能谱分析等方法研究了该合金晶间腐蚀机理.证实其晶间腐蚀是由沿晶界偏析的强化相与贫Cu区所组成的多电极体系引起的.在含Cl^－离子的中性溶液中,S相是导致晶间腐蚀的主要阳极相.S相首先发生阳极溶解,随后,贫铜区、MnAl₆相逐步随S相一起溶解.以这种方式沿晶界形成了阳极溶解通道,导致晶间腐蚀.

Study of the Simulated Test for the Intergranular Corrosion of LY12cz Al Alloy

The intermetallic compounds of θ(CuAl₂)、S(Al₂CuMg)、MnAl₆ and the pure Al(L1)were used to consist a multiple electrode system．This system was employed to simulate the grain boundary area of the LY12cz alloy．The mechanism of the intergranular corrosion of LY12cz alloy was studied by the electrochemical measurements,the SEM observation and the energy spectrum analysis with the simulate system．This paper confirmed the general believing that intergranular corrosion of the LY12cz alloy is caused by the formation of a multiple electrode system,which consist of the segregation of strengthening phases and the Cu-lack zone ,and locate along the grain boundaries．Besides,it is clear that in a Cl^- containing neutral solution,the S phase is the main anode which results in intergranular corrosion．Firstly,the anodic S phase dissolves,secondly the Cu-lack zone and MnAl6 dissolve gradually with the S phase still acts as a main anode．In this way,an anodic dissolution path forms along grain boundaries,causing intergranular corrosion．