Improvement in Recrystallization Temperature and Mechanical Properties of a Commercial TZM Alloy through Microstructure Control by Multi-Step Internal Nitriding

• Nagae Masahiro

  Division of Sustainability of Resources, Graduate School of Environmental Science, Okayama University

• Yoshio Tetsuo

  Division of Sustainability of Resources, Graduate School of Environmental Science, Okayama University

• Takada Jun

  Division of Chemical and Biological Technology, Graduate School of Natural Science and Technology, Okayama University

• Hiraoka Yutaka

  Department of Applied Physics, Faculty of Science, Okayama University of Science

Abstract

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.

Journal

• MATERIALS TRANSACTIONS

  MATERIALS TRANSACTIONS 46 (10), 2129-2134, 2005

  The Japan Institute of Metals and Materials

Keywords

• TZM alloy (Titanium–Zirconium–Molybdenum alloy)
• multi-step internal nitriding
• recrystallization temperature
• ductile-to-brittle transition temperature
• fractographic analysis
• high-temperature strength

Details

• CRID: 1390282679227618688
• NII Article ID: 130004452600
• NII Article ID: 10018277419
• NII Book ID: AA1151294X
• DOI: 10.2320/matertrans.46.2129
• ISSN: 13475320
• ISSN: 13459678
• NDL BIB ID: 7487701
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I7487701
• Web Site: https://www.jstage.jst.go.jp/article/matertrans/46/10/46_10_2129/_pdf
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
• Abstract License Flag: Disallowed