FRG: M_n+1AX_n Phase Solid Solutions: Unique Opportunities at Engineering Bulk and Surface Properties

FRG：M_n 1AX_n 相固溶体：工程体积和表面性能的独特机会

• 批准号: 0503711
• 负责人: Michel Barsoum
• 金额: --
• 依托单位: Drexel University
• 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: 2005-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0503711&HistoricalAwards=false
• 关键词: FRG; M_n+1AX_n; Phase; Solid; Solutions

NON-TECHNICAL DESCRIPTION: The properties of an emerging family of inorganic, nano-laminate engineered compounds will be investigated by a focused research group (FRG) of investigators from Drexel and Rowan Universities. These materials with the general formula Mn+1AXn (where n = 1 to 3, M is an early transition metal, A is an A-group (mostly IIIA and IVA) element and X is either C and/or N) and their solid solution alloys known as the so-called MAX phases feature unique chemical, physical, electronic and mechanical properties. They possess superb machinability and extremely low friction coefficients despite being extremely stiff materials. This combination of properties bridges some of the outstanding properties of metals and ceramics within one class of material, the MAX phases. These properties make MAX phases an ideal choice in many areas, for example those requiring low-wear, high-temperature application in aerospace, electronics, tools and consumer goods. The efforts in this program encompass a broad range of experimental and theoretical simulation tools and resources for the characterization, modeling, prediction and manipulation of properties. This program represents a partnership of Drexel, a Ph.D.-granting university, with Rowan, a four-year undergraduate university with a strong tradition of undergraduate research excellence. The linking of students, faculty and resources from both institutions will bring undergraduates and graduate students together in an interdisciplinary environment to provide broader educational and research experiences, to develop important analytical skills, to reinforce their knowledge of the materials through direct interactions, and to further stimulate interest among actively participating and talented undergraduates to pursue graduate studies in a science and engineering discipline.TECHNICAL DETAILS: The MAX phases are among the few polycrystalline solids that deform by a combination of kink and shear band formation, together with delaminations within individual grains. The unusual combination of properties is traceable to their layered structure, the metallic-covalent nature of the MX bonds that are exceptionally strong, together with M-A bonds that are relatively weak, especially in shear. While the potential of select Mn+1AXn phases for high temperature structural applications is beginning to be realized, little is understood about how their thermal, electronic and mechanical properties can be effectively tuned to produce new and unexpected combination of properties in their solid solutions. Herein we propose to explore new materials using combinatorial materials synthesis along with first-principles calculations of electronic properties and lattice dynamical calculations of MAX-phase solid solutions. With bulk and thin-film analytic experimental techniques that have proven to be successful in characterizing these phases, efficient coverage of the compositional and synthetic processing parameter space will enable rapid identification of solid solutions with attractive, and quite possibly novel, combinations of properties. Characterization will include nano-tribological measurements such as local friction and surface energy dissipation via variable temperature scanning probe microscopy; local stress-strain analysis via nanoindentation; linkage of lattice dynamics with mechanical properties via in situ Raman scattering; and probing of electronic, optical and magnetic properties in bulk and thin films.

非技术描述：新兴的无机，纳米层压工程化合物的特性将由Drexel和Rowan大学的研究人员的重点研究小组（FRG）进行研究。 这些具有通用公式Mn+1axn（其中n = 1至3的材料，M是早期过渡金属，A是A组（主要是IIIA和IVA）元素，X是C和/或N），其实心溶液合金称为所谓的最大相具有独特的化学，物理，电子和机械性能。 尽管材料极为僵硬，但它们具有出色的可加工性和极低的摩擦系数。 这种特性的组合桥接了一类材料（最大阶段）中金属和陶瓷的一些出色特性。这些属性使最大阶段成为许多领域的理想选择，例如那些需要在航空航天，电子，工具和消费品中使用低衣，高温应用的选择。该计划中的努力涵盖了广泛的实验和理论模拟工具和资源，以表征性能，建模，预测和操纵。 该计划代表了Drexel博士学位的合作伙伴关系，罗恩（Rowan）是一所四年制的本科大学，具有卓越的本科研究卓越的传统。 两家机构的学生，教职员工和资源的联系将在跨学科的环境中将本科生和研究生融合在一起，以提供更广泛的教育和研究经验，以发展重要的分析技能，通过直接互动来增强他们对材料的了解，并进一步激发积极参与和才华横溢的本科生的兴趣，以在科学和工程学科中攻读研究生研究。技术细节：最大阶段是为数不多的多晶固体之一，这些固体通过扭结和剪切带形成的结合以及单个晶粒内的分离型而变形。性质的异常组合可以追溯到其分层结构，即MX键的金属共价性质，它们与相对较弱的M-A键，尤其是在剪切中。尽管对于高温结构应用，选择的Mn+1axn相的潜力开始实现，但几乎没有什么理解的，即如何有效地调整其热，电子和机械性能，从而在其实心解决方案中产生新的和意外的特性组合。 本文中，我们建议使用组合材料合成以及对电子性质的第一原理计算以及最大相 - 相固体溶液的晶格动力学计算来探索新材料。 通过证明在表征这些阶段方面成功的批量和薄膜分析实验技术，对组成和合成处理参数空间的有效覆盖将有效地覆盖具有有吸引力且可能是新颖的特性组合的实心溶液。表征将包括通过可变温度扫描探针显微镜，例如局部摩擦和表面能量耗散等纳米底线测量。局部应力应变分析通过纳米压力；晶格动力学与机械性能通过原位拉曼散射与机械性能的联系；并探测散装和薄膜中的电子，光学和磁性。