Ca对均匀化态Mg-Bi基合金耐腐蚀性能的影响

Effect of Ca on the Corrosion Resistance of Homogeneous Mg-Bi Alloy

Mg-Bi基合金被称为“绿色金属”,被广泛应用于汽车,航空航天等领域,是开发新型镁合金的理想材料。为了弥补其耐蚀性不足的缺点,本文通过微合金化设计了一种新型的低合金化Mg-1Bi-0.3Ca镁合金,研究了0.3%Ca的添加对Mg-Bi基合金在3.5%NaCl(质量分数)溶液中的腐蚀行为。析氢失重实验和电化学实验表明,0.3%Ca元素的添加使合金的耐蚀性能提高,两种合金的Nyquist图均由一个高频容抗弧以及一个低频感抗弧组成,Mg-1Bi-0.3Ca合金的腐蚀速率最低,为0.365 mm/y。XRD和金相图结果表明,0.3%Ca元素的添加没有改变两种合金第二相种类,Mg-1Bi及Mg-1Bi-0.3Ca的第二相为Mg3Bi2相,但是Ca元素的添加改变了第二相分布。

Mg-Bi based alloys,which are ideal materials for the development of new magnesium alloys,are known as“green metals”and are widely used in automotive,aerospace and other fields.To compensate for the lack of corrosion resistance,a new type of low-alloy Mg-1Bi-0.3Ca magnesium alloy was designed by microalloying in this work,and the corrosion behavior of a Mg-Bi based alloy in a 3.5 wt.%NaCl aqueous solution was investigated by adding 0.3 wt.%Ca.Hydrogen evolution and electrochemical experiments reveal that the addition of 0.3 wt.%Ca improves the corrosion resistance of the alloys,and the Nyquist plots of the two samples consist of two loops,one high-frequency capacitive loop and one short low-frequency inductive loop.The Mg-1Bi-0.3Ca alloy has the lowest corrosion rate,with a value of 0.365 mm/y.The XRD and metallographic results show that the addition of 0.3 wt.%Ca does not change the type of second phase in either alloy,which is the Mg3Bi2 phase,but influences the distribution.