On the chemical and microstructural requirements for the pesting-resistance of Mo–Si–Ti alloys

Obert, Susanne; Kauffmann, Alexander; Seils, Sascha; Schellert, Steven; Weber, M.; Gorr, Bronislava; Christ, Hans‐Jürgen; Heilmaier, Martin

doi:10.1016/j.jmrt.2020.06.002

Cited by 34 publications

(39 citation statements)

References 35 publications

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“…The general oxidation behaviour of the eutectic Mo-20Si-52.8Ti alloy has been studied in detail in Refs. [9,11] for the as-cast and homogenised heat-treated condition with no significant differences in oxide scale formation and oxidation behaviour observed. Thus, we now focus on the detailed investigation and understanding of the formed oxide scales of the as-cast (ac) condition.…”

Section: Structural Characterisation Of the Oxide Scales Formed At 800 And 1200 °Cmentioning

confidence: 91%

“…To summarise, our previous studies focused on the chemical and microstructural conditions for achieving pesting-resistance in eutectic-eutectoid Mo-Si-Ti alloys. It turned out that a threshold in nominal Ti content of minimum 43 at% is mandatory in order to obtain adequate oxidation resistance in the pesting regime [10,11]. Moreover, it was found that the fine length scale of the eutectic microstructure is not required in order to achieve pesting-resistance since a considerably, artificially coarsened eutectic alloy exhibited a similarly good oxidation behaviour [11].…”

Section: Introductionmentioning

confidence: 99%

“…It turned out that a threshold in nominal Ti content of minimum 43 at% is mandatory in order to obtain adequate oxidation resistance in the pesting regime [10,11]. Moreover, it was found that the fine length scale of the eutectic microstructure is not required in order to achieve pesting-resistance since a considerably, artificially coarsened eutectic alloy exhibited a similarly good oxidation behaviour [11]. Thus, the chemical composition of the individual phases proved to be decisive whether pesting could be suppressed or not.…”

Section: Introductionmentioning

confidence: 99%

“…While both M5Si3 silicides (with "M" being either Ti or Mo or a combination of both), hexagonal (Ti,Mo)5Si3 and tetragonal (Mo,Ti)5Si3, exhibit an adequate oxidation resistance in the pesting regime [12,13], it is the pesting-critical MoSS phase which is responsible for the dominance of MoO3 evaporation [11]. Continuous pathways of the Ti-oxide are present in the duplex scale connecting the alloy substrate with the outer TiO2 oxide scale among all investigated Mo-Si-Ti alloys [10].…”

Section: Introductionmentioning

confidence: 99%

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Microstructural and chemical constitution of the oxide scale formed on a pesting-resistant Mo-Si-Ti alloy

et al. 2021

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Section: Structural Characterisation Of the Oxide Scales Formed At 800 And 1200 °Cmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Microstructural and chemical constitution of the oxide scale formed on a pesting-resistant Mo-Si-Ti alloy

et al. 2021

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“…As previously reported in Refs. [9,11], the lamellar eutectic colonies consisted of Mo-rich solid solution Mo ss (bright contrast) and (Ti,Mo) 5 Si 3 (dark contrast). The eutectic colonies were surrounded by a degenerated eutectic microstructure, and some primary solidification of (Ti,Mo) 5 Si 3 occurred, both of which were characteristic of the present alloy.…”

Section: Ua Powdermentioning

confidence: 99%

Flexible Powder Production for Additive Manufacturing of Refractory Metal-Based Alloys

Hinrichs¹,

Kauffmann²,

Schliephake³

et al. 2021

Metals

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The quality and properties of metal powders are essential for powder metallurgical (PM) processes in general and for additive manufacturing (AM) processing routes in particular. Thus, a variety of atomization technologies were established meeting the multiple needs of the different processing technologies. However, the production of refractory metal alloy powder remains challenging due to their high liquidus temperatures (>2000 °C), the formation of brittle intermetallic phases, as well as the reactivity with and sensitivity to interstitials of the constituting elements. In this contribution, powders made of Mo-20Si-52.8-Ti (at.%) were produced by a novel ultrasonic atomization (UA) process at laboratory-scale using an industrial electrode induction gas atomization (EIGA) process with a modified electrode concept for the first time. UA allows flexibility in alloy composition due to the arc melting-based principle, while the EIGA electrode is PM manufactured from elemental powders to provide similar flexibility on a larger scale. The powders resulting from these two processes were compared with respect to size distribution, sphericity, microstructure and phase constitution, chemical composition, and interstitial impurity content. In addition, several powder batches were produced with the UA process in order to assess the process reliability and stability. The properties, quality, and quantities of UA powders perfectly meet the requests for alloy development for powder bed fusion AM, while the modified EIGA process allows the upscaling of the alloy powder quantities.

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Phase Continuity, Brittle to Ductile Transition Temperature, and Creep Behavior of a Eutectic Mo–20Si–52.8Ti Alloy

et al. 2022

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Mo–Si–Ti alloys, like eutectic Mo–20Si–52.8Ti (at%), have previously been intensely investigated, owing to their excellent oxidation and creep resistance. To better understand high‐temperature mechanical behavior, a holistic assessment of microstructural features is necessary. Correspondingly, 3D‐focused ion beam tomography is carried out in Mo–20Si–52.8Ti. The results indicate a severely interconnected network of Mo solid solution (MoSS) and intermetallic (Ti,Mo)5Si3. Both phases retain similar network connectivity, lamellar sizes, etc. The brittle to ductile transition temperature (BDTT) is then determined through a series of bending tests and interpreted using the microstructural information. The BDTT is found to be ≈1100–1150 °C, different from Mo–9Si–8B with a continuous MoSS network. The BDTT is an immediate consequence of the continuous network of both MoSS and (Ti,Mo)5Si3. The MoSS network is instrumental in crack trapping and bridging, indicating that the present phase distribution maximized the mechanical performance over (Ti,Mo)5Si3. Having determined the network microstructure and BDTT, tensile creep behavior is evaluated and compared to previously published compressive creep results. The results show consistency in terms of strain rate, stress exponent, and microstructural features indicating a reliably good creep resistance for the network microstructure of Mo–20Si–52.8Ti regardless of loading direction.

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On the chemical and microstructural requirements for the pesting-resistance of Mo–Si–Ti alloys

Cited by 34 publications

References 35 publications

Microstructural and chemical constitution of the oxide scale formed on a pesting-resistant Mo-Si-Ti alloy

Microstructural and chemical constitution of the oxide scale formed on a pesting-resistant Mo-Si-Ti alloy

Flexible Powder Production for Additive Manufacturing of Refractory Metal-Based Alloys

Phase Continuity, Brittle to Ductile Transition Temperature, and Creep Behavior of a Eutectic Mo–20Si–52.8Ti Alloy

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