Reaction sintering of NiAl and TiB2-NiAl composites under pressure
Reaction sintering of NiAl and TiB2-NiAl composites under pressure
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DOI：
10.1016/s0921-5093(98)00862-4
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发表时间：
1998-12
期刊：
影响因子：
6.4
通讯作者：
S. Bhaumik;C. Divakar;L. Rangaraj;A. Singh
中科院分区：
文献类型：
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作者：
S. Bhaumik;C. Divakar;L. Rangaraj;A. Singh
金属间化合物基复合材料是一种新型的工程材料，用于氧化和腐蚀环境中的高温结构应用。在本研究中，已经尝试合成TiB 2-NiAl复合材料，其中基体相NiAl通过反应合成原位产生。复合材料与10，15和30体积%，采用高压反应烧结（HPRS）和反应热压（RHP）方法，以元素Ni和Al为原料，以TiB 2为烧结体制备NiAl合金。HPRS和RHP分别在3GPa和900°C以及20 MPa和1650°C下进行。通过X射线衍射和显微结构研究确定了烧结体中的不同相。在HPRS中，反应是不完全的，这产生了各种中间相（Ni 2Al 3，Ni 3Al）。为了获得具有单相NiAl基体的TiB_2-NiAl复合材料，必须在1100°C下对这些压坯进行退火。HPRS压块的密度为99%。硬度和断裂韧性值分别在10至20 GPa和3.9至5.7 MPa·m的范围内。RHP压坯除了HPRS压坯中存在的那些相之外还含有AlB 2、Ni 2B和NiTi 2相。RHP复合材料完全致密。与HPRS获得的材料相比，这些材料具有上级硬度（15-22 GPa），但断裂韧性（2.9-3.8 MPa·m）较差。
Intermetallic matrix composites are a new class of engineering materials for high temperature structural applications in oxidizing and aggressive environments. Attempts have been made in the present investigation to synthesize TiB2–NiAl composites, in which the matrix phase NiAl was produced in situ by reaction synthesis. The composites with 10, 15 and 30 vol.%NiAl were fabricated from the mixtures of elemental Ni and Al and TiB2powders by high pressure reaction sintering (HPRS) and reactive hot pressing (RHP). The HPRS and RHP were carried out at 3 GPa and 900°C, and 20 MPa and 1650°C, respectively. The different phases in the sintered compacts were identified by X-ray diffraction and microstructural studies. In HPRS, the reaction was incomplete which gave rise to various intermediate phases (Ni2Al3, Ni3Al). It was necessary to anneal these compacts at 1100°C to obtain TiB2–NiAl composites with single phase NiAl matrix. The densities of the HPRS compacts were ∼99%. The hardness and fracture toughness values were in the range 10 to 20 GPa and 3.9 to 5.7 MPa√m, respectively. The RHP compacts contained AlB2, Ni2B and NiTi2phases in addition to those present in the HPRS compacts. The RHP composites were fully dense. These had superior hardness (15–22 GPa) but inferior fracture toughness (2.9–3.8 MPa√m) compared to those obtained by HPRS.