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Analysis of the Microstructure, Phase Composition, and Oxidation Kinetics of Heat-Resistant Titanium Alloys with Gadolinium
Physics of Metals and Metallography ( IF 1.2 ) Pub Date : 2020-05-19 , DOI: 10.1134/s0031918x20040110
A. A. Popov , M. O. Leder , M. C. Karabanalov , E. N. Popova , I. V. Narygina

Abstract

The structure, phase composition, and local chemical composition of half-finished products (rods) made from Ti–Al–Mo–Zr–Si- and Ti–Al–Mo–Zr–Sn–Si-based alloys additionally microalloyed with 0.4 wt % gadolinium have been studied in this work. The structure of the rod made from the Gd-alloyed Ti–Al–Mo–Zr–Si composition was found to be characterized by the presence of Gd2O3 gadolinium oxide particles. The structure of the rod made from the Gd-alloyed Ti–Al–Mo–Zr–Sn–Si composition, which contains tin as a low-melting element, is characterized by the presence of Gd–Sn–O complex oxide particles, whose cores and shells are Gd5Sn3 intermetallics and Gd2O3 gadolinium oxide, respectively. The formation of such particles in both alloys occurs at the stage of ingot solidification, and the particles remain in the materials at all stages of their subsequent treatment. The oxidation kinetics of the alloys upon isothermal holding in a temperature range of 600–800°С is studied depending on the structure of half-finished products. The oxidation processes of the Ti–Al–Mo–Zr–Sn–Si alloy are less intensive than those of the Ti–Al–Mo–Zr–Si alloy. The alloying with gadolinium up to 0.4 wt % leads to the accelerated oxidation of the tin-free alloy, which is due to the presence of Gd2O3 particles precipitated at grain boundaries and interfaces. The alloying of the tin-containing composition with gadolinium almost does not affect the oxidation kinetics at 600–700°С and slightly decelerates the oxidation at 750–800°С; this is related to the presence of the Gd–Sn–O oxide particles in the structure, which are uniformly distributed over the grain body. The laws of oxidation of both the compositions free from gadolinium and alloyed with gadolinium were determined. It was shown that the oxide film formed upon the oxidation of both alloys is multilayer and consists of alternating layers of aluminum and titanium oxides. In this case, the progressive growth of oxide film layers alters the film exfoliation owing to the high brittleness of aluminum oxides. The presence of gadolinium oxide particles in both alloys leads to the porosity of diffusion zone of the base metal upon oxidation.



中文翻译:

含with耐热钛合金的组织,相组成和氧化动力学

摘要

由Ti–Al–Mo–Zr–Si-和Ti–Al–Mo–Zr–Sn–Si-Si基合金制成的半成品(棒)的结构,相组成和局部化学组成,这些合金还微合金化有0.4 wt this已在这项工作中进行了研究。发现由Gd合金Ti-Al-Mo-Zr-Si组成的棒的结构特征在于存在Gd 2 O 3氧化ado颗粒。由Gd合金的Ti-Al-Mo-Zr-Sn-Si组合物制成的棒结构,其中包含锡作为低熔点元素,其特征在于存在Gd-Sn-O复合氧化物颗粒,其氧化物核和壳是Gd 5 Sn 3金属间化合物和Gd 2 O 3氧化oxide分别。两种合金中此类颗粒的形成均发生在铸锭凝固阶段,并且颗粒在其后续处理的所有阶段均保留在材料中。根据半成品的结构,研究了等温保持在600–800°С范围内的合金的氧化动力学。Ti-Al-Mo-Zr-Sn-Si合金的氧化过程强度不如Ti-Al-Mo-Zr-Si合金。与g含量不超过0.4 wt%的合金导致无锡合金加速氧化,这是由于存在Gd 2 O 3颗粒在晶界和界面处沉淀。含锡的成分与g的合金化几乎不会影响600-700°С的氧化动力学,而会稍微降低750-800°С的氧化。这与结构中存在Gd-Sn-O氧化物颗粒有关,它们均匀地分布在晶粒体内。确定了不含from并与g形成合金的两种组合物的氧化定律。结果表明,两种合金氧化后形成的氧化膜都是多层的,由铝和钛氧化物的交替层组成。在这种情况下,由于氧化铝的高脆性,氧化物膜层的逐渐生长改变了膜的剥离。

更新日期:2020-05-19
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