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Mechanical Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

2002

Physics

Iowa State University

Articles 1 - 3 of 3

Full-Text Articles in Mechanical Engineering

Simulation Of Chemical Mechanical Planarization Of Copper With Molecular Dynamics, Y. Ye, Rana Biswas, Ashraf F. Bastawros, Abhijit Chandra Sep 2002

Simulation Of Chemical Mechanical Planarization Of Copper With Molecular Dynamics, Y. Ye, Rana Biswas, Ashraf F. Bastawros, Abhijit Chandra

Aerospace Engineering Publications

With an aim to understanding the fundamental mechanisms underlying chemical mechanical planarization ~CMP! of copper, we simulate the nanoscale polishing of a copper surface with molecular dynamics utilizing the embedded atom method. Mechanical abrasion produces rough planarized surfaces with a large chip in front of the abrasive particle, and dislocations in the bulk of the crystal. The addition of chemical dissolution leads to very smooth planarized copper surfaces and considerably smaller frictional forces that prevent the formation of bulk dislocations. This is a first step towards understanding the interplay between mechanistic material abrasion and chemical dissolution in chemical mechanical planarization ...


Three-Dimensional Landau Theory For Multivariant Stress-Induced Martensitic Phase Transformations. Ii. Multivariant Phase Transformations And Stress Space Analysis, Valery I. Levitas, Dean L. Preston Jan 2002

Three-Dimensional Landau Theory For Multivariant Stress-Induced Martensitic Phase Transformations. Ii. Multivariant Phase Transformations And Stress Space Analysis, Valery I. Levitas, Dean L. Preston

Valery I. Levitas

In this paper, the three-dimensional Landau model of austenite-martensite transformations constructed in Part I is generalized to include transformations between an arbitrary number of martensitic variants. The model can incorporate all temperature-dependent thermomechanical properties of both phases for arbitrary crystal symmetries, including higher-order elastic constants, and it correctly describes the characteristic features of stress-strain curves for shape-memory alloys and steels, namely, constant transformation strain tensors, constant or weakly temperature dependent stress hysteresis, and transformation at nonzero tangent moduli. Geometric representations of the conditions for phase equilibrium and phase transformations in six-dimensional stress space are developed. For the cubic-tetragonal phase transformation ...


Three-Dimensional Landau Theory For Multivariant Stress-Induced Martensitic Phase Transformations. I. Austenite↔Martensite, Valery I. Levitas, Dean L. Preston Jan 2002

Three-Dimensional Landau Theory For Multivariant Stress-Induced Martensitic Phase Transformations. I. Austenite↔Martensite, Valery I. Levitas, Dean L. Preston

Valery I. Levitas

A three-dimensional Landau theory of stress-induced martensitic phase transformations is presented. It describes transformations between austenite and martensitic variants and transformations between martensitic variants. The Landau free energy incorporates all temperature-dependent thermomechanical properties of both phases. The theory accounts for the principal features of martensitic transformations in shape memory alloys and steels, namely, stress-strain curves with constant transformation strain and constant, or weakly temperature dependent, stress hysteresis, as well as nonzero tangent elastic moduli at the phase transformation point. In part I, the austenite↔martensite phase transformation is treated, while transformations between martensitic variants are considered in part II.