Corrosion Mechanisms in Amorphous Alloys: Critical Compositional and Structural Defects for Local Corrosion

非晶合金的腐蚀机制：局部腐蚀的关键成分和结构缺陷

• 批准号: 0504983
• 负责人: John Scully
• 金额: $ 36万
• 依托单位: University of Virginia Main Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-15 至 2009-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0504983&HistoricalAwards=false
• 关键词: Corrosion; Mechanisms; Amorphous; Alloys; Critical

TECHNICAL: The outstanding local corrosion resistance and excellent passivity of amorphous metallic materials is often attributed to the elimination of microstructural heterogeneity. However, identification of the exact governing critical defect is lacking and competing explanations exist. In both traditional glass materials as well as newer bulk metallic glass alloys, this generic question concerning the fundamental origins of excellent corrosion resistance remain unresolved. As long as the mechanism is unclear, the impacts of partial devitrification on corrosion cannot be forecast. In this regard, there are a number of unresolved issues and he opportunity exists to clarify these issues through careful selection of model alloys that enable rejection or acceptance of each hypothesis for corrosion resistance. Regarding the critical flaw size, selected amorphous alloys can be partially devitrified by primary crystallization to form isolated solute rich and/or solute lean crystals in a remaining solute rich amorphous matrix which serve as model materials that enable exploration of a range of non-uniformities. The mechanism for good corrosion resistance when a non-uniformity is below the critical size will be determined in complimentary multidisciplinary studies. Several testable hypotheses for the good corrosion resistance of small nonuniformities in an amorphous matrix will be explored. Regarding the need to separate the roles of structural from compositional non-uniformities, the opportunity exists to explore this issue through selection of alloys which undergo devitrification without change in composition. For example, certain Fe- B, Co-B, Cu-Zr and Al-Sm amorphous alloys can devitrify by polymorphous crystallization to form crystalline solid solutions of the same composition. In addition, , origins of corrosion of the heat-treated amorphous matrix will be studied focusing on the role(s) of structural and compositional relaxation of the amorphous phase in nano-scale roughening by corrosive dissolution. NON-TECHNICAL: Broader implications include human resource development. The CESE trains students in the multidisciplinary area of corrosion, materials science/engineering and surface science and is a major supplier of materials professionals with corrosion knowledge to US industry, government and academia. Under represented gender and ethnic students have and will continue to be a focus of integrated training and research endeavor on this grant. Integration of research and education is accomplished at UVA through dual role of research from NSF supported activities in both theses/degrees and for external publication, presentation and knowledge creation/dissemination. Students, as well as the PI, disseminate results in broad interest papers, specialty papers, conferences, and lab tours/demos for K-12 students.

技术支持：非晶态金属材料优异的抗局部腐蚀性能和优良的钝化性能通常归因于其微观结构的不均匀性。 然而，缺乏对确切的关键缺陷的识别，并且存在相互竞争的解释。在传统玻璃材料和较新的块体金属玻璃合金中，有关优异耐腐蚀性的根本来源的这个普遍问题仍未得到解决。 只要机理不清楚，就无法预测部分失透对腐蚀的影响。 在这方面，有许多未解决的问题，他的机会存在，以澄清这些问题，通过仔细选择的模型合金，使拒绝或接受每一个假设的耐腐蚀性。关于临界缺陷尺寸，所选的非晶合金可以通过初级结晶而部分地失透，以在剩余的富含溶质的非晶基质中形成孤立的富含溶质和/或贫溶质的晶体，其用作能够探索一系列非均匀性的模型材料。当不均匀性低于临界尺寸时，良好耐腐蚀性的机制将在互补的多学科研究中确定。 几个可测试的假设，良好的耐腐蚀性的小不均匀性，在非晶基体将进行探讨。关于需要将结构不均匀性与成分不均匀性的作用分开，存在通过选择经历失透而不改变成分的合金来探索这个问题的机会。例如，某些Fe- B、Co-B、Cu-Zr和Al-Sm非晶合金可以通过多晶结晶而失透，以形成相同组成的结晶固溶体。此外，将研究热处理的非晶基体的腐蚀的起源，重点是非晶相的结构和成分弛豫在通过腐蚀溶解的纳米尺度粗糙化中的作用。非技术性：更广泛的影响包括人力资源开发。CESE培训腐蚀，材料科学/工程和表面科学多学科领域的学生，是美国工业，政府和学术界具有腐蚀知识的材料专业人员的主要供应商。代表性不足的性别和种族学生已经并将继续成为该补助金综合培训和研究奋进的重点。研究和教育的整合是通过从NSF支持的活动在论文/学位和外部出版，演示和知识创造/传播研究的双重作用在UVA完成。学生以及PI在广泛的兴趣论文、专业论文、会议和K-12学生的实验室图尔斯/演示中传播结果。