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Title: Microstructures and Mechanical Properties of in-situ V-V 3B 2 Composites

Abstract

A series of binary V-B alloys, with compositions spanning the eutectic, were produced by arc melting and drop casting. Microstructural examination revealed that the fully eutectic structure occurs at V-11B rather than V-15B as reported in the V-B phase diagram (all compositions in at.%). The V-11B eutectic was directionally solidified in an optical floating zone furnace, resulting in a composite microstructure consisting of a V matrix and flake or trigonal shaped V3B2 phase. The boride flake spacing ({umlt e}) decreases with increasing growth rate (R), following the relation {umlt e}2.56R=C, where C is a constant. TEM observations showed that the orientation relationship between the V and V3B2 phases is given by: (001)V // (001)V3B2 and (100)V // (100)V3B2. The growth direction and the V/V3B2 interface are parallel to the (001) direction and (100) planes in the two phases, respectively. Tensile tests were used to investigate the temperature dependence of the strength and ductility of the composite. At temperatures to 600 C, the yield strength of the eutectic is about 140 MPa higher than that of a commonly used vanadium solid-solution alloy, V-4Cr-4Ti. Surprisingly, the eutectic shows 5% tensile ductility at room temperature which increases to 10% as the test temperaturemore » is raised to 800 C.« less

Authors:
 [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
931558
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: 2006 MRS Fall Meeting, Boston, MA, USA, 20061127, 20061130
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; EUTECTICS; MECHANICAL PROPERTIES; PHASE DIAGRAMS; TEMPERATURE DEPENDENCE; YIELD STRENGTH; VANADIUM

Citation Formats

Xie, Sujing, and George, Easo P. Microstructures and Mechanical Properties of in-situ V-V3B2 Composites. United States: N. p., 2007. Web.
Xie, Sujing, & George, Easo P. Microstructures and Mechanical Properties of in-situ V-V3B2 Composites. United States.
Xie, Sujing, and George, Easo P. Mon . "Microstructures and Mechanical Properties of in-situ V-V3B2 Composites". United States. doi:.
@article{osti_931558,
title = {Microstructures and Mechanical Properties of in-situ V-V3B2 Composites},
author = {Xie, Sujing and George, Easo P},
abstractNote = {A series of binary V-B alloys, with compositions spanning the eutectic, were produced by arc melting and drop casting. Microstructural examination revealed that the fully eutectic structure occurs at V-11B rather than V-15B as reported in the V-B phase diagram (all compositions in at.%). The V-11B eutectic was directionally solidified in an optical floating zone furnace, resulting in a composite microstructure consisting of a V matrix and flake or trigonal shaped V3B2 phase. The boride flake spacing ({umlt e}) decreases with increasing growth rate (R), following the relation {umlt e}2.56R=C, where C is a constant. TEM observations showed that the orientation relationship between the V and V3B2 phases is given by: (001)V // (001)V3B2 and (100)V // (100)V3B2. The growth direction and the V/V3B2 interface are parallel to the (001) direction and (100) planes in the two phases, respectively. Tensile tests were used to investigate the temperature dependence of the strength and ductility of the composite. At temperatures to 600 C, the yield strength of the eutectic is about 140 MPa higher than that of a commonly used vanadium solid-solution alloy, V-4Cr-4Ti. Surprisingly, the eutectic shows 5% tensile ductility at room temperature which increases to 10% as the test temperature is raised to 800 C.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

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