Thermomechanical processing and high-temperature behavior of spark-plasma-sintered near-α Ti-8242NbS alloy

Research output: ThesisMaster's Thesis


Near-α titanium alloys show high potential for high-temperature applications in aerospace, automotive and nautical industries. This alloying class combines high strength, low density as well as good creep and oxidation resistance. Current scientific research focuses on developing reinforced near-α titanium alloys which can be used above 600 °C. In this thesis the thermomechanical processing and the high-temperature behavior were investigated of a new near-α titanium alloy, called Ti8242NbS, manufactured by spark-plasma-sintering. Thermomechanical processing routes were defined in the first steps to achieve fully-lamellar, bi-lamellar and bi-modal microstructures and compare them in terms of suitability for high-temperature service. Heat treatments at different temperatures and dwell times were performed to investigate the precipitation kinetics at elevated temperatures. The results have shown that precipitation hardening effects reaches its maximum at 397 HV5 with a fully-lamellar microstructure after aging at 670 °C for 24 h. The subsequent TEM investigations have shown that the hardness increase of about 20 HV5 is based on finely distributed Ti3Al-particles inside the α-lamellae. The mechanical characterization of this work consisted of tensile and creep experiments on different specimen states. It was shown that precipitation hardening of Ti8242NbS alloy at 650 °C had increased the yield strength by 40 MPa, while simultaneously decreasing the total elongation to a minimum value of 0.24 %. The creep experiments have shown that aged Ti8242NbS alloy with fully-lamellar microstructure exhibits the minimal creep rate of 1.0∙10^(-8) s^(-1) and thus performs better than the Ti6242S alloy. Final oxidation tests also showed the advantage of the Ti8242NbS alloy over the Ti6242S alloy for high-temperature application.
Translated title of the contributionThermomechanische Verarbeitung und Hochtemperaturverhalten einer "Spark Plasma" gesinterten Near-Alpha Ti-8242NbS Legierung
Original languageEnglish
Awarding Institution
  • Montanuniversität
  • Clemens, Helmut, Supervisor (internal)
Award date8 Apr 2022
Publication statusPublished - 2021

Bibliographical note

no embargo


  • High-temperature-alloy
  • Precipitation hardening
  • Near-α titanium alloy
  • Creep resistance
  • Oxidation resistance
  • Thermomechanical processing

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