Preparation of Ti-Al intermetallic compounds by spark plasma sintering
Preparation of Ti-Al intermetallic compounds by spark plasma sintering
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DOI：
10.1007/s11661-001-0101-2
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发表时间：
2001-03
期刊：
影响因子：
--
通讯作者：
B. Mei;Y. Miyamoto
中科院分区：
文献类型：
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作者：
B. Mei;Y. Miyamoto
基于Ti^ sub - 3^ Al （α ^ sub - 2^）和TiAl （γ）化学计量的钛铝化物具有优异的潜力，成为一些最重要的航空航天材料，因为它们具有高耐火性质、低密度、高比强度、高熔化温度和高温耐环境性。[1,2,3]在Ti-Al二元体系中有三个主要相（Ti^ sub - 3^ Al， TiAl和TiAl^ sub - 3^ Al）虽然基于Ti^ sub 3^ Al的各种az合金具有合理的室温延展性，但由于强度损失，过度氧化和氢渗透的敏感性，它们的高温应用受到限制。增加铝的含量来生产γ - tial合金可以改善所有这些性能，但随之而来的是降低室温延展性和韧性的损失，也就是说，相对于γ - tial， α ^ sub 2^-Ti^ sub 3^ Al的含量对于Ti-Al金属间化合物的性能是重要的。因此，通过组织控制，可以改善其某些性能。由于钛铝化物的偏析，传统的熔炼或铸造工艺不利于其性能的改善，因此人们正在寻找许多替代技术来生产这些金属间化合物。另一种替代方法是火花等离子烧结（SPS），这种方法正受到越来越多的关注。[4,5]该方法的流程示意图如图1所示。该方法通过给粉末颗粒之间的间隙充上电能，并有效地施加瞬时产生的高温火花等离子体，使低温烧结和烧结结合在短时间内成为可能。与传统方法相比，它具有操作方便、烧结能量控制准确、烧结速度快、重复性高、安全可靠等优点。
Titanium aluminides based on Ti^ sub 3^ Al (alpha^ sub 2^) and TiAl (gamma) stoichiometries have excellent potential to become some of the most important aerospace materials because of their high refractory nature, low densities, high specific strength, high melting temperature, and environmental resistance at elevated temperature.[1, 2, 3] There are three main phases (Ti^ sub 3^ Al, TiAl, and TiAl^ sub 3^) in the Ti-Al binary system.[2] While various az alloys based on Ti^ sub 3^ Al possess reasonable room-temperature ductility, their high-temperature applications are limited due to loss of strength, excessive oxidation, and susceptibility to hydrogen permeation. Increasing the aluminum content to produce gamma-TiAl alloys can improve all of these properties but with the attendant penalty of reducing room-temperature ductility and toughness,[2] that is, the contents of alpha^ sub 2^-Ti^ sub 3^ Al relative to gamma-TiAl are important as regards the properties of Ti-Al intermetallic compounds. Therefore, through microstructure control, some of their properties can be improved.The conventional melting or casting route of fabrication of titanium aluminides is unfavorable to improving their properties owing to segregation, resulting in many alternative techniques for producing these intermetallics being sought. One alternative method is spark plasma sintering (SPS), which is receiving increased attention.[4, 5] The process diagram of this method is schematically shown in Figure 1. This method makes possible sintering and sinter bonding at a low temperature for a short period by charging the intervals between powder particles with electrical energy and effectively applying a high-temperature spark plasma generated momentarily. It has many advantages over conventional methods, including ease of operation and accurate control of sintering energy as well as high sintering speed, high reproducibility, safety, and reliability.