Kinetic Study of the Solid-State Transformation of Vacuum-Plasma-Sprayed Ti-6Al-4V Alloy

被引:0
作者
H. R. Salimijazi
Z. A. Mousavi
M. A. Golozar
J. Mostaghimi
T. Coyle
机构
[1] Isfahan University of Technology,Materials Engineering Department
[2] University of Toronto,Centre for Advanced Coating Technologies
来源
Journal of Thermal Spray Technology | 2014年 / 23卷
关键词
heat treatment; net-shape forming; Ti-6Al-4V; vacuum plasma spray; characterization; TTT diagram;
D O I
暂无
中图分类号
学科分类号
摘要
Because of the nature of the plasma spraying process, the physical and mechanical properties of vacuum-plasma-sprayed structures of Ti-6Al-4V alloy are completely different from those of conventionally manufactured alloys such as bulk materials from casting and forging. To obtain desired mechanical and physical properties, vacancy and internal defects must be reduced, splat boundaries must be eliminated, and optimal phase compositions should be obtained through postdeposition heat treatments. To determine appropriate heat treatment processes, one needs to study the kinetic behavior of the as-sprayed microstructure at elevated temperatures. In the current study, the kinetics of the solid transformations found in Ti-6Al-4V alloys produced during the vacuum plasma spraying process was studied based on the Johnson-Mehl-Avrami theory. For the kinetic behavior of this alloy, the nonconstant temperature dependence of the transformation rate constant exhibits an irregularity at 900 °C, marking a change in the transformation mechanism. For the lower-temperature (<900 °C) curves, the constant gradient indicates a lack of change in the transformation mechanism, including homogeneous nucleation, with growth of α phase. For higher temperatures (>900 °C), a gradient change indicates a change in the transformation mechanism. The first mechanism was the formation of α-phase grain boundary, and the second mechanism was α-plate nucleation and growth from grain boundaries. The value of the transformation rate constant in the kinetics study of as-sprayed Ti-6Al-4V alloy was much higher than for material produced by the casting method. Using the results obtained from the kinetics of the β→α+β\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \upbeta \to \upalpha + \upbeta $$\end{document} phase transformation at different constant temperatures, a time–temperature–transformation (TTT) diagram for as-sprayed Ti-6Al-4V alloy was developed.
引用
收藏
页码:31 / 39
页数:8
相关论文
共 33 条
[1]  
Tamirisakandala S(2003)Recent Advances in the Deformation Processing of Titanium Alloys J. Mater. Eng. Perform. 12 661-673
[2]  
Vedam BV(2002)Resistivity Study and Computer Modeling of the Isothermal Transformation Kinetics of Ti-8Al-1Mo-1V Alloy J. Alloy. Compd. 333 122-132
[3]  
Bhat RB(2001)Resistivity Study and Computer Modeling of the Isothermal Transformation Kinetics of Ti-6Al-4V, Ti-6Al-2Sn-4Zr-2Mo-0.08Si Alloys J. Alloy. Compd. 314 181-192
[4]  
Malinove S(2004)Metallography and Microstructures of Titanium and Its Alloys Metall. Microstruct. ASM Handb. ASM Int. 9 899-917
[5]  
Markovsky P(2004)Solidification Structures of Titanium Alloys Metall. Microstruct. ASM Handb. ASM Int. 9 116-126
[6]  
Sha W(2006)Vacuum Plasma Spraying: A New Concept for Manufacturing Ti-6Al-4V Structure JOM 58 50-56
[7]  
Malinove S(2007)Understanding Grain Growth and Pore Elimination in Vacuum-Plasma-Sprayed Titanium Alloy Metall. Mater. Trans. A 38A 476-484
[8]  
Markovsky P(2004)Understanding Plasma Spraying J. Phys. D Appl. Phys. 37 86-108
[9]  
Sha W(2007)Study of Solidification Behavior and Splat Morphology of Vacuum Plasma Sprayed Ti Alloy by Computational Modeling and Experimental Results Surf. Coat. Technol. 201 7924-7931
[10]  
Guo Z(2005)Microstructure and Failure Mechanism in As-Deposited Vacuum Plasma Sprayed Ti-6Al-4V Alloy J. Therm. Spray Technol. 14 215-223