Determination of Phase Equilibria by Experiment of Calonlation in F-Al-X Ternary System

F-Al-X三元体系相平衡实验测定

• 批准号: 07650811
• 负责人: TAKEYAMA Masao
• 金额: $ 1.41万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650811/
• 关键词: Till; Phase equilibria; Lattice stability; Transition peritectaid; Ternary entectic; Phase stability; 相安定性; マッシブ変態; 包共析反応; 組織制御; γ-TiAl; α_2-Ti_3Al; 3相共存領域; 冷却速度

Phase equilibria among the beta (bcc or B2), alpha (hcp) and gamma (L1_0) phases in Ti-Al-M ternary systems at elevated temperatures have been studied, where the M is beta stabilizing element for pure titanium. The beta (B2) +alpha+gamma three-phase coexisting region exists at temperatures above 1473 K,and it moves towrds a direction of high aluminum and high M concentrations with increasing temperature. The change in the phase equilibria by the addition M is associated with the alpha<tautomer>beta allotropic transformation temperature of pure titanium and can be thermodynamically interpreted in terms of the lattice stability ratios LAMBDA of M to Ti. The LAMBDA for beta against alpha in ternary Ti-Al-M systems, for example, is defined as follows : LAMBDA^<beta*alpha>_i=DELTAﾟG^<beta*alpha>_/DELTAﾟG^<beta*alpha>_. The DELTAﾟG^<beta*alpha>_ refers to the difference in Gibbs free energy between bcc (beta) structure and hcp (alpha) structure for pure M, and DELTAﾟG^<beta*alpha>_ that for … More pure titanium. The values of LAMBDA^<beta*alpha>_i for each element is nearly equal to 10 and at least one oeder of magnitude larger than those of LAMBDA^<alpha*gamma>_i. The reason the LAMBDA^<beta*alpha>_i has a large positive value for each element is that the value of DELTAﾟG^<beta*alpha>_ is fairly smaller than that of DELTAﾟG^<beta*alpha>_, since the temperature to be interest is only 300 K away from the beta*alpha allotropic transformation temperature T^<beta/alpha>_ (1155 K) of pure Ti. When the temperature raises and the difference in temperature from the T^<beta/alpha>_ becomes large, the value of DELTAﾟG^<beta*alpha>_ almost remains unchanged whereas that of DELTAﾟG^<beta*alpha>_ increases, leading to a smaller value of LAMBDA^<beta*alpha>_i. This is responsible for the three-phase coexisting region moving toward the direction of high aluminum and high M concentration as temperature increases.At the temperature below the alpha<tautomer>alpha_2 congruent temperature T^b_ in the binary system (T^b_ : 1452K), alpha_2-Ti_3aL phase appears as a stable phase as well, together with the other three phases. We identified that the beta+alpha+gamma three-phase coexisting region at higher temperatures changes to beta+alpha_2+gamma three-phase coexisting region at lower temperatures through a transition peritectoid reaction (beta+alpha<tautomer>alpha_2+gamma) when the thrid element M stablizes the alpha_2 phase against alpha phase. Less

本文研究了Ti-Al-M三元体系中β （bcc或B2）、α (hcp)和γ (L1_0)相在高温下的相平衡，其中M是纯钛的β稳定元素。在1473 K以上存在β (B2) + α + γ三相共存区，并随着温度的升高向高铝高M方向发展。添加M对相平衡的改变与纯钛的α <互变异构体> β同素异形体转变温度有关，并且可以用M与Ti的晶格稳定比LAMBDA进行热力学解释。例如，三元Ti-Al-M体系中β对α的λ定义如下：λ ^< β * α >_i=DELTA G^< β * α >_/DELTA G^< β * α >_。δ G^< β * α >_表示纯M的bcc （β）结构和hcp （α）结构的吉布斯自由能差，δ G^< β * α >_表示纯钛的δ G^< β * α >_表示纯钛的吉布斯自由能差。对于每个元素，LAMBDA^<beta*alpha bbb_i的值几乎等于10，并且至少比LAMBDA^<alpha*gamma bbb_i的值大一个数量级。λ ^< β * α >_i对各元素具有较大的正值的原因是δ G^< β * α >_的值比δ G^< β * α >_的值要小得多，因为所研究的温度距离纯Ti的β * α同素异向转变温度T^< β / α >_ （1155 K）仅300 K。当温度升高，与T^< β / α >_的温差变大时，δ G^< β * α >_的值基本保持不变，而δ G^< β * α >_的值增大，导致δ G^< β * α >_i的值变小。这是随着温度的升高，三相共存区向高铝、高M浓度方向发展的原因。在二元体系中低于α <互变异构体> α _2同温T^b_ （T^b_: 1452K）的温度下，α _2- ti_3al相也与其他三个相一起作为稳定相出现。我们发现，当第三元素M稳定α - 2相时，高温下的β + α + γ三相共存区通过过渡周反应（β + α <互变异构体> α - 2+ γ）转变为低温下的β + α - 2+ γ三相共存区。少

项目成果

M.Takeyama, M.Horikoshi, Y.Ohmura and T.Matsuo: "Decomposition of High-temperature alpha Phase in Gamma TiAl Alloy" Proc.Int.Conf.on Thermec '97, TMS. Vol.2. 148-1496 (1997)

M.Takeyama、M.Horikoshi、Y.Ohmura 和 T.Matsuo：“γ TiAl 合金中高温 α 相的分解”Proc.Int.Conf.on Thermec 97，TMS。

M.TAKEYAMA et al.: "Phase equilibria among α,α_2,β and γ phases in ternary Ti-Al-X systems at elevated temperatures" Titanium 95,Science and Technology,The Institute of Materials. 294-301 (1996)

M.TAKEYAMA 等：“高温下三元 Ti-Al-X 体系中 α、α_2、β 和 γ 相的相平衡”Titanium 95，科学与技术，材料研究所 294-301 (1996)。

竹山雅夫 他1名: "γ-TiAl合金における相平行と組織形成-Ti-Al 2元系合金に及ぼす大3元素の影響-" まてりあ,日本金属学会報. 35-10. 1058-1064 (1996)

Masao Takeyama 等 1：“γ-TiAl 合金中的相平行性和结构形成 - 三种主要元素对 Ti-Al 二元合金的影响”，日本金属学会通报 35-1064。 ）

S.Kobayashi et al.: "Phase Equilibria and Phase Stability among β,α,α_2 and γ Phases in Ti-Al-M Ternary Systems at Elevated Temperatures" Proceedings of PRICM 3,TMS. (in press). (1998)

S. Kobayashi 等人：“高温下 Ti-Al-M 三元体系中 β、α、α_2 和 γ 相的相平衡和相稳定性”，PRICM 3，TMS（出版中）。

M.Takeyama, Y.Katho and M.Kikuchi: "Phase Equilibria among alpha, alpha_2, beta and gamma Phases in Ternary Ti-Al-X Systems at Elevated Temperatures" Titanium 95, The Institue of Metals. Vol.1. 294-301 (1996)

M.Takeyama、Y.Katho 和 M.Kikuchi：“高温下三元 Ti-Al-X 系统中 α、α_2、β 和 γ 相之间的相平衡”Titanium 95，金属研究所。