Strength and deformation mechanism of tungsten wires exposed to high temperature annealing: Impact of potassium doping. (November 2018)

• Record Type: Journal Article
• Authors: Terentyev, D.; Riesch, J.; Lebediev, S.; Khvan, T.; Dubinko, A.; Bakaeva, A.
• Is Part Of: International journal of refractory metals & hard materials. Volume 76(2018)
• Page Start: 226
• Page End: 233
• Publication Date: 2018-11
• Subjects: Tungsten -- Fiber -- Plasticity -- Recrystallization -- Potassium doped -- Annealing -- Composites; Heat resistant alloys -- Periodicals; Refractory materials -- Periodicals; Metallography -- Periodicals; Alliages réfractaires -- Périodiques; Matériaux réfractaires -- Périodiques; Métallographie -- Périodiques; Heat resistant alloys; Metallography; Refractory materials; Periodicals; Electronic journals; 669.73
• DOI: 10.1016/j.ijrmhm.2018.07.002
• Languages: English
• ISSNs: 0263-4368

Abstract

Abstract: Recent efforts dedicated to the assessment of mechanical properties of tungsten wires, as means for fiber-reinforced composites, have shown that potassium (K) doping in the as-drawn state does not modify the mechanical properties of the wire. High temperature annealing (Ta up to 2300 °C) leads to the severe embrittlement of the wire associated with the loss of fracture strength. In this work, we assess the transition behavior of pure and K-doped W wires exposed to the annealing in the temperature range of 1000–2300 °C to identify and recommend temperatures suitable for operation and fabrication of the fiber-reinforced composites. The results of mechanical tests performed in the temperature range of RT-500 °C are reported and substantiated by the electron microscopy analysis. Room temperature tests demonstrate that pure W wires become fully brittle after annealing above 1300 °C, whereas K-doped wires loses ductility above 2100 °C. With raising the test temperature to 300–500 °C, it is found that the strength of pure W wire reduces by a factor of two at Ta = 1000 °C (as compared to non-annealed wire), and goes down to 100 MPa at Ta = 1900 °C. The K-doping suppresses the reduction of the fracture strength at least up to Ta = 1900 °C, thus offering a temperature gap of ~600 °C for the use as reinforcement. Highlights: Effect of high temperature annealing on mechanical properties is studied in tungsten wire. Potassium doping retains good strength of W wire up to 1900 °C. Annealing at 1600 °C and above causes complete embrittlement of pure W wire.