Development of a Highly-Transferable Analytic Bond-Order Potential for the Tin+1AlCn MAX Phases
Gabriel is a first year CoorsTek fellow, having joined the Compuational Materials Science and Design (CMSD) group of Dr. Garritt Tucker as a Ph.D. student in 2018. Prior to this, he completed his BS and MS degrees in Materials Science and Engineering at Drexel University, graduating with a 4.0 cumulative GPA. For his MS thesis, he studied the fundamental mechanical strength of two-dimensional MXenes, including the effects of point defects and chemical composition using atomistic modeling methods. His current research focus in the CMSD group is the development of atomistic models for two-dimensional and layered materials, with the goal of further understanding their fundamental deformation mechanisms.
MAX phases are a large family of layered, ternary metal carbides and nitrides with the chemical formula Mn+1AXn, in which M is an early transition metal, A is an A-group element, X is C and/or N, and n = 1, 2, or 3. Described as “thermodynamically stable nanolaminates,” MAX phases possess a unique combination of metallic and ceramic properties owing to their layered structure. While MAX phases have been recognized as remarkable materials and are utilized in a wide variety of applications, an understanding of their fundamental deformation mechanisms is still lacking. Recent studies indicate atomic scale ripples, termed ripplocations, to be the operative deformation mechanism rather than dislocations, as previously thought. Atomistic modeling studies would contribute greatly to resolving this outstanding issue, but currently no interatomic potentials exist for MAX phases, owing to the number and diversity of different interactions present. Analytic bond order potentials (ABOPs), which have been successfully applied to a range of systems encompassing metallic, covalent, and ionic bonding, offer a potential solution. Herein, an ABOP is developed for the Tin+1AlCn MAX phases via a unique fitting procedure, which is easily transferable to a number of other MAX phases. Accuracy of the potential is demonstrated by calculation of known structural, elastic, defect, and thermal properties. Preliminary results, making use of the ABOP, are presented to show the unique deformation behavior of MAX phases upon indentation. Deformation behavior in other applications of interest such as metal-MAX nanolaminates and radiation environments is also considered. The fundamental insight gained from these atomistic studies will allow for better engineering of MAX phases to fully take advantage of their unique properties.