Interactive effects of cyclic oxidation and structural evolution for Ti-6Al-4V/(TiC TiB) alloy composites at elevated temperatures
Interactive effects of cyclic oxidation and structural evolution for Ti-6Al-4V/(TiC TiB) alloy composites at elevated temperatures
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Ti-6Al-4V/(TiC TiB) 合金复合材料在高温下循环氧化和结构演化的相互作用
DOI：
10.1016/j.jallcom.2018.04.118
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发表时间：
2018
影响因子：
6.2
通讯作者：
Geng L
中科院分区：
文献类型：
--
作者：
Wei S L;Huang L J;Li X T;An Q;Geng L
研究了反应热压法制备的TiC+TiB杂化网络增强Ti-6Al-4V复合材料的显微组织特征和高温抗氧化性能。杂化增强剂的不均匀分布导致{\ α}-Ti基体相发生应力诱导的晶粒细化，外加界面上的非均质形核进一步促进了晶粒细化。HRTEM分析表明，TiB与α -Ti相的晶体取向关系为（201）TiB//(-1100) α -Ti + [11-2]//[0001] α -Ti， TiC与{\ α}-Ti相的晶体取向关系为（-200）TiC//(-2110) {\ α}-Ti和[001]TiC//[01-10] α -Ti。混合增强Ti-6Al-4V/(TiC+TiB)复合材料分别在873、973和1073 K下循环氧化100 h时，对烧结基体合金和单纯添加TiC或TiB增强的两种复合材料均表现出优异的抗氧化性能，混合增强材料体积分数比基体合金粉末尺寸对抗氧化性能的影响更大。当温度从873 K上升到1073 K时，氧化动力学由近抛物线型经过拟线性趋势转变为最终的线性模式。这与氧化鳞片从连续的保护膜到部分受损层的形态转变相对应，最终导致氧化铝和金红石交替多层的完全剥落。提出了一种现象模型来解释氧化鳞片的生长过程。热应力的释放、氧扩散的抑制和氧化物粘附的加强是增强复合材料抗氧化性能的三个主要机制。
The microstructural features and high-temperature oxidation resistance of hybrid (TiC+TiB) networks reinforced Ti-6Al-4V composites were investigated after fabricated with reaction hot pressing technique. The inhomogeneous distribution of hybrid reinforcers resulted in a sort of stress-induced grain refinement for {\alpha}-Ti matrix phase, which was further facilitated by heterogeneous nucleation upon additive interfaces. HRTEM analyses revealed the crystallographic orientation relation between TiB and alpha-Ti phases as (201)TiB//(-1100)alpha-Ti plus [11-2]//[0001] alpha-Ti, while TiC and {\alpha}-Ti phases maintained the interrelation of (-200)TiC//(-2110) {\alpha}-Ti and [001]TiC//[01-10] alpha-Ti. The hybridly reinforced Ti-6Al-4V/(TiC+TiB) composites displayed superior oxidation resistance to both the sintered matrix alloy and the two composites reinforced solely with TiC or TiB addition during the cyclic oxidation at 873, 973 and 1073 K respectively for 100 h. The hybrid reinforcers volume fraction was a more influential factor to improve oxidation resistance than the matrix alloy powder size. As temperature rose from 873 to 1073 K, the oxidation kinetics transferred from the nearly parabolic type through qusilinear tendency into the finally linear mode. This corresponded to the morphological transition of oxide scales from a continuous protective film to a partially damaged layer and ended up with the complete spallation of alternating alumina and rutile multilayers. A phenomenological model was proposed to elucidate the growth process of oxides scales. The release of thermal stress, the suppression of oxygen diffusion and the fastening of oxide adherence were found as the three major mechanisms to enhance the oxidation resistance of hybrid reinforced composites.