Sc对Al-3Cu-1Li合金显微组织和电化学腐蚀行为的影响

用真空熔炼炉制备Al-3Cu-1Li-xSc(x=0、0.1%、0.3%和0.5%)合金,观察合金的显微组织,测量合金的维氏硬度。在0.1mol/L NaCl溶液中,用开路电位(OCP)、极化曲线、电化学阻抗谱(EIS)和Mott-Schottky曲线研究了Sc对Al-3Cu-1Li合金腐蚀行为的影响。结果表明:Sc细化了合金的显微组织,提高了合金硬度;Sc添加后未改变合金的电化学腐蚀机制,该合金热力学稳定性提高的同时耐蚀性有所降低;该合金的耐蚀性与其腐蚀产物膜的载流子密度高低具有相关性。

Effect of α phase on evolution of oxygen-rich layer on titanium alloys

In order to understand the evolution of oxygen-rich layer (ORL) on titanium alloys, the near α titanium alloy TA15 and α+β type titanium alloy TC4 were thermally exposed in air at 850 °C to evaluate the effect of α phase content on formation and evolution of ORL, and the stability and diffusion of oxygen in α- and β-Ti were investigated by first principles calculations to reveal the oxygen diffusion rate. TA15 with more α phases has a higher diffusion coefficient of ORL evolution than TC4, resulting in forming thicker ORL on TA15 under the same thermal exposure condition. The first principles calculations indicate that octahedral interstice of α-Ti is the most stable site for oxygen atom. The nearest neighbor diffusion between octahedral interstices along the [0001] direction in α-Ti presenting the lowest activation energy is the most favorable oxygen diffusion mechanism in α- and β-Ti.

Mg-3Li和Mg-3Li-1Sc合金直接化学镀镍工艺研究

选用真空熔炼Mg-3Li和Mg-3Li-1Sc合金为实验材料,在以Ni2SO4为主盐的溶液中对其进行化学镀镍。以主盐和还原剂的配比、施镀温度和时间为变量,进行正交实验,对获得的化学镀镍层进行形貌观察,并用3.5%NaCl水溶液全浸实验评价镀层的耐蚀性。结果表明:主盐与还原剂配比为1∶1时两种合金镀层耐蚀性较高;最优温度与时间为:90℃/3 h(Mg-3Li)和80℃/2 h(Mg-3Li-1Sc)。