Structure-environmental performance relationship studies of wrought mg alloys with an aim towards increasing their utilization in the transportation industries

通过使用轻质合金来减少汽车的总质量是提高燃油效率和减少有害排放的方法之一。镁合金部件具有高的比强度和比刚度，为实现这些目标提供了重要的机会。然而，制约变形镁合金产品广泛应用的主要技术问题有两个，一是生产效率相对较低，二是高强度、高塑性和高耐蚀性相结合的新合金的开发。拟议的研究计划将制定战略，通过改善对与变形镁铝锌合金相关的环境退化的了解和预测来提高耐腐蚀性。为此，本研究将表征和阐明(1)晶体取向对非合金单晶和多晶镁上形成的准钝化膜的结构、成分和稳定性的影响，以及(2)多晶镁铝锌合金中金属间化合物相的组成、尺寸和分布对微电偶活动的影响，作为合金含量和形变加工路线(板材、挤压和锻件)的函数。将利用微米和纳米级分辨率探测技术的全面组合来实现这些目标。利用高分辨电子显微镜可以获得基体、金属间化合物相和钝化膜的结构和成分信息，而利用高分辨扫描电化学探针技术(SKP和SVP)可以获得基体和金属间化合物相的局域电化学活性。至少有三名HQP将接受这项提议的培训。除了帮助汽车业实现燃油经济性、排放和性能的减重目标外，与HQP共同开发的技术还将创造出一种加拿大的“专有技术”，将有效地支持国内供应商的创新努力。

Reducing the overall mass of automobiles by the use of lightweight alloys is one of the means by which improved fuel efficiency and reduced harmful emissions can be attained. Mg alloy components, with their high specific strength and stiffness, provide significant opportunities to achieve these goals. However, there are two major technological issues preventing widespread application of wrought Mg alloy products, namely the relatively low production rate and the development of new alloys with a combination of high strength, high ductility and high corrosion resistance. The proposed research program will develop strategies to improve the corrosion resistance by achieving an improved understanding and prediction of the environmental degradation associated with wrought Mg-Al-Zn alloys. To this end, the research will characterize and elucidate the influence of (1) crystallographic orientation on the structure, composition and stability of the quasi-passive film formed on unalloyed single crystal and polycrystalline Mg, and (2) composition, size & distribution of intermetallic phases on the micro-galvanic activity in polycrystalline Mg-Al-Zn alloys, as a function of the alloy content, and the thermomechanical processing route (sheet, extrusions and forgings). An encompassing combination of micro- and nano-scale resolution probe techniques will be utilized to achieve these goals. Structural and compositional information on the matrix, intermetallic phases and passive film will be obtained using high resolution electron microscopy, whereas the localized electrochemical activity of the matrix and intermetallic phases will be obtained using high resolution scanning electrochemical probe techniques (SKP and SVP). A minimum of three HQP will be trained in this proposal. In addition to helping the industry attain their weight reduction targets for fuel economy, emissions and performance, the technology developed with the HQP will create a Canadian "know-how" that will effectively support innovation efforts of domestic suppliers.