General features of high temperature deformation kinetics for γ-TiAl-based alloys with DP/NG microstructures: Part I. A survey of mechanical data and development of unified rate-equations
General features of high temperature deformation kinetics for γ-TiAl-based alloys with DP/NG microstructures: Part I. A survey of mechanical data and development of unified rate-equations
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DOI：
10.1016/j.msea.2016.08.079
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发表时间：
2016-12-15
期刊：
影响因子：
6.4
通讯作者：
Bouzy, Emmanuel
中科院分区：
文献类型：
--
作者：
Cheng, Liang;Li, Jinshan;Bouzy, Emmanuel
近二十年来，γ - ti基合金因其低密度、高比强度、优异的蠕变和抗氧化性等优点而受到人们的广泛关注，被认为是有前途的高温应用材料。众所周知，tial基合金中存在四种典型的组织，即全层状（FL）、近层状（NL）、双相（DP）和近γ (NG)。FL/NL-TiAl合金具有优良的抗蠕变等高温力学性能，但变形性能相对较低。DP/NG-TiAl合金具有较好的成形性，但抗蠕变性能降低。因此，DP/NG的显微组织更适合热加工，并被认为是二次加工的先决条件，本文主要研究了DP/NG- tial合金的高温变形行为。迄今为止，人们对各种DP/NG-TiAl合金的变形动力学或力学性能进行了大量的研究，并积累了大量的实验数据。为了探讨其高温变形动力学的一般特征，本文对近二十年来发表的各种DP/NG-TiAl合金的拉伸/压缩力学数据进行了总结和综述。确定了三种变形机制（位错蠕变、晶界滑动和扩散蠕变），并对每种变形机制的主要因素（即合金成分、组织和晶粒尺寸）对变形动力学的影响进行了详细的分析和讨论。结果表明：除含碳TiAl合金等分散硬化合金外，DP/NG-TiAl合金的高温变形动力学对成分的敏感性较低；相反，γ晶粒尺寸成为主要的限制因素。在此基础上，成功地推导出了一系列统一的速率方程。(C) 2016 Elsevier B.V.版权所有
gamma-TiAl-based alloys have attracted intense attentions in the past two decades and are regarded as promising candidate materials for high-temperature applications due to their low density, high specific strength, superior creep and oxidation resistance, etc. It is well known that there are four typical microstructures in TiAl-based alloys, namely, full-lamellar (FL), near-lamellar (NL), duplex (DP) and near gamma (NG). The FL/NL-TiAl alloys possess superior high temperature mechanical performance such as creep resistance, but their deformability is relatively lower. In contrast, the DP/NG-TiAl alloys have much better formability while the creep resistance is reduced. Hence the DP/NG microstructure is preferable for hot-working and thought to the prerequisite for secondary processing, and the present paper is primarily focused on the high temperature deformation behavior of DP/NG-TiAl alloys. Till date, considerable research efforts have been directed towards the deformation kinetics or mechanical properties of various DP/NG-TiAl alloys, and a mass of experimental data has been accumulated. In order to explore their general features of high temperature deformation kinetics, in this paper the tensile/compression mechanical data of various DP/NG-TiAl alloys from the literature published in the past twenty years has been summarized and reviewed. Three deformation mechanisms (dislocation creep, grain boundary sliding and diffusion creep) have been identified, and for each the effects of major factors (i.e., alloy composition, microstructure and grain size) on deformation kinetics have been analyzed and discussed in detail. The results revealed that the high temperature deformation kinetics of DP/NG-TiAl alloys is less sensitive to composition except some dispersion-hardened alloys such as carbon-containing TiAl alloys. Instead, the gamma grain size became the major limiting factor. Based on this observation, a series of unified rate-equations has been successfully developed. (C) 2016 Elsevier B.V. All rights reserved.