Properties of Titanium Zirconium Molybdenum Alloy after Exposure to Indium at Elevated Temperatures

Abstract

Titanium zirconium molybdenum (TZM) is a high strength at high temperature alloy with favorable properties for use in high temperature structural applications. Use of TZM in high pressure, gas-containing autoclave systems was recently demonstrated for the ammonothermal method. Use of indium (In) in the system is desired, though there is a general lack of literature and understanding on the corrosion and impact of In on the mechanical properties of TZM. This study reports for the first time the mechanical properties of TZM after exposure to metallic In at temperatures up to 1000 °C. Static corrosion testing of TZM in In were performed at 750 °C and 1000 °C for 14 days. A microstructure analysis was performed suggesting no visible alteration of the grain structure. Differential thermal analysis (DTA) was performed to investigate compound formation between In and the primary constituents of TZM yielding no measurable reactions and hence no noticeable compound formation. X-ray energy dispersive spectroscopy (EDS) line scans across the TZM-In interface revealed no measurable mass transport of In into the TZM matrix. These results were confirmed using X-ray diffraction (XRD). Given the apparent inertness of TZM to In, mechanical properties of TZM after exposure to In were measured at test temperatures ranging from 22 °C to 800 °C and compared to unexposed, reference TZM samples from the same material stock. Tensile properties, including ultimate tensile strength, yield strength and total elongation, were found to be comparable between In-exposed and unexposed TZM samples. Impact fracture toughness testing (Charpy) performed at temperatures ranging from −196 °C to 800 °C showed that TZM is unaffected upon exposure to In. Tensile testing indicated ductile behavior at room temperature (slow strain rate) whereas impact testing (high strain rate) suggested a ductile to brittle transition temperature between 100 °C and 400 °C. Given these results, TZM appears to be a promising candidate for use as a force bearing material when exposed to In at high temperature.

High-Energy Computed Tomography as a Prospective Tool for In Situ Monitoring of Mass Transfer Processes inside High-Pressure Reactors—A Case Study on Ammonothermal Bulk Crystal Growth of Nitrides including GaN

“…Nevertheless, the material has successfully been used as load-bearing material for ammonothermal autoclaves with operating temperatures up to 900 °C [ 35 ]. In addition, the chemical stability of TZM makes it a promising candidate for liner-free ammonothermal syntheses of Indium-containing materials [ 39 ]. Of the considered alloys, Inconel 718 possesses the highest yield strength at moderate temperatures; however, the low onset of age hardening around 620 °C ( Table 4 ) and the decrease in yield strength at higher temperatures limits the operating temperature to 600 °C or slightly above.…”

Ammonothermal Crystal Growth of Functional Nitrides for Semiconductor Devices: Status and Potential

“…Ductility (often evaluated by fracture toughness) is also an important consideration, especially from a safety point of view. This is a particular concern in the case of the molybdenum-based alloy TZM, for which the brittle-to-ductile transition occurs above room temperature, specifically at 100 to 150 °C [164] or even 400 °C depending on the strain rate [312].…”

Prospective view of nitride material synthesis

“…38,39 While molybdenum and its alloys are reported not to have as high of a yield strength as nickel-chrome alloys and therefore require greater wall thicknesses in order to meet safety requirements, they have been shown to stand up to basic and acidic environments without liners and without degradation suggesting that molybdenum is a viable "universal" autoclave base material for exploration of a large set of nitride material synthesis. 40 While these options effectively open up the chemistry playing field for mineralizers, developments in measurements of autoclave fluid and temperature dynamics in situ have seen promising progress toward shortening the development time for ammonothermal processes. Perhaps the simplest process outputs are pressure and temperature.…”

“…Another alternative in autoclave equipment is the use of molybdenum for the autoclave body 38,39 . While molybdenum and its alloys are reported not to have as high of a yield strength as nickel–chrome alloys and therefore require greater wall thicknesses in order to meet safety requirements, they have been shown to stand up to basic and acidic environments without liners and without degradation suggesting that molybdenum is a viable “universal” autoclave base material for exploration of a large set of nitride material synthesis 40 …”