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Title: Shock synthesis of silicides; 2: Thermodynamics and kinetics

Abstract

A thermodynamic and kinetic analysis of shock-induced reactions in the (Nb or Mo)-Si systems provides a framework for the extraordinarily high reaction rates and a quantitative interpretation of the experimental results obtained in Part 1. The thermodynamic analysis is conducted by adding the heat of reaction to the shock energy; increases in shock pressure, temperature, and velocity are predicted. At the particle level, melting at the silicon-metal interface is found to be a necessary condition for the initiation of reaction; heat conduction calculations enable the prediction of a critical molten (Si) region size for which the heat generated through the reaction exceeds the heat lost to the unreacted regions. The calculation of melt fraction (of Si) as a function of shock energy for the initiation of shock-induced reaction. At the local level, the reaction kinetics can be rationalized through the production of a liquid-phase reaction product (NbSi[sub 2]), the formation of spherical nodules of this product through interfacial tension to melt niobium along the interface which facilitates both the expulsion of the NbSi[sub 2] nodules into the liquid Si, and the generation of fresh Nb interface for further reaction. In addition, the dissolved Nb enriches the surrounding Si liquid, promotingmore » more NbSi[sub 2] reaction and formation.« less

Authors:
; ;  [1]
  1. (Univ. of California, San Diego, La Jolla (United States). Dept. of Applied Mechanics and Engineering Sciences)
Publication Date:
OSTI Identifier:
5150208
Resource Type:
Journal Article
Journal Name:
Acta Metallurgica et Materialia; (United States)
Additional Journal Information:
Journal Volume: 42:3; Journal ID: ISSN 0956-7151
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; MOLYBDENUM SILICIDES; REACTION KINETICS; THERMODYNAMIC PROPERTIES; NIOBIUM SILICIDES; QUANTITATIVE CHEMICAL ANALYSIS; SHOCK HEATING; CHEMICAL ANALYSIS; HEATING; KINETICS; MOLYBDENUM COMPOUNDS; NIOBIUM COMPOUNDS; PHYSICAL PROPERTIES; PLASMA HEATING; REFRACTORY METAL COMPOUNDS; SILICIDES; SILICON COMPOUNDS; TRANSITION ELEMENT COMPOUNDS; 360204* - Ceramics, Cermets, & Refractories- Physical Properties; 400201 - Chemical & Physicochemical Properties

Citation Formats

Meyers, M.A., Lihsing Yu, and Vecchio, K.S. Shock synthesis of silicides; 2: Thermodynamics and kinetics. United States: N. p., 1994. Web. doi:10.1016/0956-7151(94)90269-0.
Meyers, M.A., Lihsing Yu, & Vecchio, K.S. Shock synthesis of silicides; 2: Thermodynamics and kinetics. United States. doi:10.1016/0956-7151(94)90269-0.
Meyers, M.A., Lihsing Yu, and Vecchio, K.S. Tue . "Shock synthesis of silicides; 2: Thermodynamics and kinetics". United States. doi:10.1016/0956-7151(94)90269-0.
@article{osti_5150208,
title = {Shock synthesis of silicides; 2: Thermodynamics and kinetics},
author = {Meyers, M.A. and Lihsing Yu and Vecchio, K.S.},
abstractNote = {A thermodynamic and kinetic analysis of shock-induced reactions in the (Nb or Mo)-Si systems provides a framework for the extraordinarily high reaction rates and a quantitative interpretation of the experimental results obtained in Part 1. The thermodynamic analysis is conducted by adding the heat of reaction to the shock energy; increases in shock pressure, temperature, and velocity are predicted. At the particle level, melting at the silicon-metal interface is found to be a necessary condition for the initiation of reaction; heat conduction calculations enable the prediction of a critical molten (Si) region size for which the heat generated through the reaction exceeds the heat lost to the unreacted regions. The calculation of melt fraction (of Si) as a function of shock energy for the initiation of shock-induced reaction. At the local level, the reaction kinetics can be rationalized through the production of a liquid-phase reaction product (NbSi[sub 2]), the formation of spherical nodules of this product through interfacial tension to melt niobium along the interface which facilitates both the expulsion of the NbSi[sub 2] nodules into the liquid Si, and the generation of fresh Nb interface for further reaction. In addition, the dissolved Nb enriches the surrounding Si liquid, promoting more NbSi[sub 2] reaction and formation.},
doi = {10.1016/0956-7151(94)90269-0},
journal = {Acta Metallurgica et Materialia; (United States)},
issn = {0956-7151},
number = ,
volume = 42:3,
place = {United States},
year = {1994},
month = {3}
}