Improvement in Recrystallization Temperature and Mechanical Properties of a Commercial TZM Alloy through Microstructure Control by Multi-Step Internal Nitriding
Improvement in Recrystallization Temperature and Mechanical Properties of a Commercial TZM Alloy through Microstructure Control by Multi-Step Internal Nitriding
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DOI：
10.2320/matertrans.46.2129
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发表时间：
2005-10
影响因子：
1.2
通讯作者：
M. Nagae;T. Yoshio;J. Takada;Y. Hiraoka
中科院分区：
文献类型：
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作者：
M. Nagae;T. Yoshio;J. Takada;Y. Hiraoka
为了开发具有高再结晶温度和优异机械性能的钼合金，通过光学和透射电子显微镜、断口分析和三点弯曲试验，对商用TZM合金（钛锆钼合金）的多步内部氮化进行了研究。在 1423 至 1873 K 之间的温度下进行了两种类型的氮化工艺，一种是两步工艺，另一种是四步工艺。通过四步氮化，即使在 1 mm 厚的样品中心，再结晶也被完全抑制，而在两步氮化的情况下，再结晶在样品中心进行。通过四步氮化将TZM合金在真空中的再结晶温度提高到1973 K以上。氮化 TZM 合金的韧脆转变温度 (DBTT) 很大程度上取决于变形微观结构的厚度。四步氮化试样的DBTT低于130 K，比两步氮化试样低约70 K。 1773 K 下四步氮化试样的屈服应力约为再结晶试样的 2.6 倍。
In order to develop a molybdenum alloy with high recrystallization temperature and excellent mechanical properties, multi-step internal nitriding of a commercial TZM alloy (Titanium–Zirconium–Molybdenum alloy) was studied through optical and transmission electron microscopy, fractographic analysis and three-point bending tests. Two types of nitriding processes, a two-step and another four-step process, were carried out at temperatures between 1423 and 1873 K. Recrystallization was completely suppressed, even at the center of a 1-mm-thick specimen through four-step nitriding, whereas recrystallization proceeded at the specimen center in the case of two-step nitriding. The recrystallization temperature of the TZM alloy in vacuum was raised above 1973 K by four-step nitriding. The ductile-to-brittle transition temperature (DBTT) of the nitrided TZM alloy depended strongly on the thickness of the deformed microstructure. DBTT of the four-step nitriding specimen was below 130 K, which is about 70 K lower than that of the two-step nitriding specimen. The yield stress of the four-step nitriding specimen at 1773 K was about 2.6 times as large as that of the recrystallized specimen.