Correlation between microstructure and properties of fine grained Mo–Mo3Si–Mo5SiB2 alloys

Krüger, Manja; Jain, P.; Kumar, Keshav; Heilmaier, Martin

doi:10.1016/j.intermet.2013.10.025

Cited by 80 publications

(31 citation statements)

References 38 publications

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“…It is noticeable that the microhardness of the supersaturated solid solution powders produced by MA is significantly higher than the values measured in bulk V-Si-B and Mo-Si-B materials in the respective Mo ss [22] and V ss phases [31], with values of about 9 or 7 GPa, respectively. This is due to supersaturation of Si and B in the V or Mo lattice by the MA process compared to the near-equilibrium state after the sintering processes.…”

Section: Description Of the Occurring Process Mechanismsmentioning

confidence: 67%

Similarities and Differences in Mechanical Alloying Processes of V-Si-B and Mo-Si-B Powders

Krüger

Schmelzer

Helmecke

2016

Metals

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V-Si-B and Mo-Si-B alloys are currently the focus of materials research due to their excellent high temperature capabilities. To optimize the mechanical alloying (MA) process for these materials, we compare microstructures, morphology and particles size as well as hardness evolution during the milling process for the model alloys V-9Si-13B and Mo-9Si-8B. A variation of the rotational speed of the planetary ball mill and the type of grinding materials is therefore investigated. These modifications result in different impact energies during ball-powder-wall collisions, which are quantitatively described in this comparative study. Processing with tungsten carbide vials and balls provides slightly improved impact energies compared to vials and balls made of steel. However, contamination of the mechanically alloyed powders with flaked particles of tungsten carbide is unavoidable. In the case of using steel grinding materials, Fe contaminations are also detectable, which are solved in the V and Mo solid solution phases, respectively. Typical mechanisms that occur during the MA process such as fracturing and comminution are analyzed using the comminution rate K P . In both alloys, the welding processes are more pronounced compared to the fracturing processes.

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Section: Description Of the Occurring Process Mechanismsmentioning

confidence: 67%

Similarities and Differences in Mechanical Alloying Processes of V-Si-B and Mo-Si-B Powders

Krüger

Schmelzer

Helmecke

2016

Metals

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“…The cracks are impeded at the interface between the Laves phase and the Mo-rich BCC 2 phase, which indicates that ductile phase toughening is effective for suppressing crack propagation. 23,24) Zhu et al 25) evaluated the fracture toughness of the NbCr 2 Laves phase, which is around 0.9 MPa ffiffiffiffi m p , by Vickers indentation testing using:…”

Section: Temperature Dependence Of Microstructural Evolutionmentioning

confidence: 99%

Microstructural Evolution and Mechanical Properties of a Three-Phase Alloy in the Cr–Mo–Nb System

Ikeda

Horiuchi

et al. 2019

Mater. Trans.

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A new three-phase alloy of 50Cr30Mo20Nb (at%) was studied based on the CrMoNb ternary phase diagram, and was composed of a Cr-rich BCC 1 phase, a Mo-rich BCC 2 phase and a NbCr 2 Laves phase after heat treatment at around 1523 K or lower. A supersaturated BCC single-phase solid solution alloy obtained by homogenization at 1973 K for 1 h underwent microstructural evolution during heat treatment at 1473 K. Intragranular precipitation of the Cr-rich BCC 1 phase occurred, which led to the formation of an alternating BCC 1 /BCC 2 two-phase microstructure through a discontinuous precipitation process, followed by precipitation of the Laves phase at the BCC 1 /BCC 2 interphase boundaries. At a higher temperature of 1523 K, a similar microstructure was observed, with increased BCC decomposition and Laves precipitation rates, while the alloy consisted of BCC and Laves phases at 1773 K. The mechanical properties of alloys heat treated at 1473 K for various periods after the solid-solution treatment were also investigated. A maximum fracture strength of 1493 MPa and a minimum hardness of 773 « 7 HV were obtained for an alloy aged for 24 h, where the BCC 1 /BCC 2 two-phase microstructure dominated. The Vickers hardness of an alloy aged for 72 h, which had a fine-grained microstructure that included the Laves phase, was 839 « 8 HV under a load of 0.5 kgf, and no obvious microcracks were observed. [

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“…This has been observed already for similar trials in the Mo-Si-B system. 17 However, the hexagonal structure of titanium and hafnium limits the solubility of those two elements in the niobium bcc matrix even during the off-equilibrium process of mechanical alloying so that some amount of Ti and Hf is present as fine lamellae (Fig. 9).…”

Section: Characterization Of Ma Powdermentioning

confidence: 99%

Influence of Powder Metallurgical Processing Routes on Phase Formations in a Multicomponent NbSi-Alloy

Seemüller

Hartwig

Mulser

et al. 2014

JOM

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Refractory metal silicide composites on the basis of Nb ss -Nb 5 Si 3 have been investigated as potential alternatives for nickel-base superalloys for years because of their low densities and good high-temperature strengths. NbSibased composites are typically produced by arc-melting or casting. Samples in this study, however, were produced by powder metallurgy because of the potential for near net-shape component fabrication with very homogeneous microstructures. Either gas atomized powder or high-energy mechanically alloyed elemental powders were compacted by powder injection molding or hot isostatic pressing. Heat treatments were applied for phase stability evaluation. Slight compositional changes (oxygen, nitrogen, or iron) introduced by the processing route, i.e., powder production and consolidation, can affect phase formations and phase transitions during the process. Special focus is put on the distinction between different silicides (Nb 5 Si 3 and Nb 3 Si) and silicide modifications (a-, b-, and c-Nb 5 Si 3 ), respectively. These were evaluated by x-ray diffraction and energy-dispersive spectroscopy measurements with the additional inclusion of thermodynamic calculations using the calculated phase diagram method.

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Correlation between microstructure and properties of fine grained Mo–Mo3Si–Mo5SiB2 alloys

Cited by 80 publications

References 38 publications

Similarities and Differences in Mechanical Alloying Processes of V-Si-B and Mo-Si-B Powders

Similarities and Differences in Mechanical Alloying Processes of V-Si-B and Mo-Si-B Powders

Microstructural Evolution and Mechanical Properties of a Three-Phase Alloy in the Cr–Mo–Nb System

Influence of Powder Metallurgical Processing Routes on Phase Formations in a Multicomponent NbSi-Alloy

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