scholarly journals Modern Powder Metallurgy: Chemical Composition Design for Improved Heat Resistant Alloys

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1215
Author(s):  
Igor Razumovskii ◽  
Alla Logacheva ◽  
Vsevolod Razumovskiy ◽  
Ivan Logachev ◽  
Mikhail Razumovsky
Keyword(s):  
Powder Metallurgy ◽  
Grain Boundaries ◽  
Hot Isostatic Pressing ◽  
Cohesion Energy ◽  
Alloy Matrix ◽  
Modern Approach ◽  
Fine Grained ◽  
Heat Resistant ◽  
Polycrystalline Alloys ◽  
Molar Energy

The modern approach to the design of heat-resistant metal alloys (HRAs) is analyzed, according to which the creep rupture characteristics of an alloy are mostly determined by the strength of interatomic bonding at grain boundaries (GBs) and in the bulk of a matrix phase. The main attention is paid to the concept of “low alloying additions” to polycrystalline alloys with transition metals, because of which the cohesive strength of the GBs and the cohesion energy of the alloy matrix are increased. This approach is especially important in relation to alloys obtained by powder metallurgy, which, in the compacted state, are fine-grained polycrystals. The methodology for calculating the key parameters of the theory (the energy of impurity segregation to the grain boundaries Egb and to the free surface Efs, as well as the values of the partial molar energy of the cohesion of the alloys) from the first principles is given. The results of applying the theory to the study of Ni-, Cr- and Ti-based alloys and the development of new HRAs based on them are presented. Typical defects in the microstructures of objects obtained using additive technologies (AT) and the application efficiency of standard methods of processing powder alloys (Hot Isostatic Pressing (HIP), heat treatment (HT)) to improve the microstructure and increase the mechanical properties are considered.

scholarly journals Evaluation of Hot Workability of Powder Metallurgy Ni-Based Superalloy with Different Initial Microstructures

2020 ◽  
Vol 52 (1) ◽  
pp. 181-193
Author(s):  
Masaya Higashi ◽  
Naoya Kanno
Keyword(s):  
Grain Size ◽  
Powder Metallurgy ◽  
Strain Rate ◽  
Hot Isostatic Pressing ◽  
Hot Extrusion ◽  
Strain Rate Range ◽  
Coarse Grained ◽  
Hot Workability ◽  
Fine Grained ◽  
Nucleation Sites

AbstractThe effect of the initial microstructure on the hot workability of a powder metallurgy Ni-based superalloy was investigated in the high-temperature range of 950 °C to 1180 °C and strain rate range of 0.001 to 1.0 s−1. Six samples with different initial microstructures were fabricated by various hot isostatic pressing (HIP) conditions and subsequent treatments such as hot extrusion. The coarse-grained samples exhibited low hot workability regardless of the deformation conditions. In contrast, the hot workability of the fine-grained samples significantly varied depending on the deformation conditions. The hot workability exhibited a peak at the sub-solvus temperature of ~ 1100 °C and decreased at temperatures higher and lower than this temperature. In addition, the hot workability decreased monotonically with increasing the strain rate. The prior particle boundaries (PPBs) acted as cavity nucleation sites and crack paths, especially at lower temperatures and higher strain rates, resulting in early fracture and low hot workability. With decreasing the grain size, the hot workability at the peak temperature improved. The extruded sample with the smallest grain size exhibited the best hot workability, owing to the avoidance of PPB fracture and the acceleration of dynamic recrystallization.

Calculation of plasma centrifugal spraying parameters of fine granules of heat-resistant nickel alloys

2020 ◽  
pp. 471-474
Author(s):  
M.G. Yagodin ◽  
E.I. Starovoytenko
Keyword(s):  
Powder Metallurgy ◽  
Nickel Alloys ◽  
Dynamic Pressure ◽  
Calculated Data ◽  
Powder Size ◽  
Metal Powders ◽  
Heat Resistant ◽  
Gas Dynamic ◽  
Spraying Parameters ◽  
Wide Range

The equipment for the production of wide range of metal powders purposed for powder metallurgy is described. The possibility for producing of powders by the plasma centrifugal spraying is considered taking into account the gas dynamic pressure. The calculated data on the powder size for different materials are given.

Ultra-Fine Grained Ti-15Mo Alloy Prepared by Powder Metallurgy

2018 ◽  
Vol 941 ◽  
pp. 1276-1281
Author(s):  
Anna Terynková ◽  
Jiří Kozlík ◽  
Kristína Bartha ◽  
Tomáš Chráska ◽  
Josef Stráský
Keyword(s):  
Powder Metallurgy ◽  
Bulk Material ◽  
Alpha Phase ◽  
Full Density ◽  
Fine Grained ◽  
Cryogenic Milling ◽  
Aircraft Manufacturing ◽  
Plasma Sintering ◽  
Beta Matrix ◽  
Spark Plasma

Ti-15Mo alloy belongs to metastable β-Ti alloys that are currently used in aircraft manufacturing and Ti15Mo alloy is a perspective candidate for the use in medicine thanks to its biotolerant composition. In this study, Ti15Mo alloy was prepared by advanced techniques of powder metallurgy. The powder of gas atomized Ti-15Mo alloy was subjected to cryogenic milling to achieve ultra-fine grained microstructure within the powder particles. Powder was subsequently compacted using spark plasma sintering (SPS). The effect of cryogenic milling on the microstructure and phase composition of final bulk material after SPS was studied by scanning electron microscopy. Sintering at 750°C was not sufficient for achieving full density in gas atomized powder, while milled material could be successfully sintered at this temperature. Alpha phase particles precipitated during sintering and their size, as well as the size of beta matrix grains, was strongly affected by the sintering temperature.

scholarly journals Evolution of the Microstructure and Mechanical Properties of a Ti35Nb2Sn Alloy Post-Processed by Hot Isostatic Pressing for Biomedical Applications

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1027
Author(s):  
Joan Lario ◽  
Ángel Vicente ◽  
Vicente Amigó
Keyword(s):  
Powder Metallurgy ◽  
Mechanical Strength ◽  
Room Temperature ◽  
Hot Isostatic Pressing ◽  
Phase Changes ◽  
Post Processing ◽  
Isostatic Pressing ◽  
Porosity Reduction ◽  
Processing Step ◽  
Hip Process

The HIP post-processing step is required for developing next generation of advanced powder metallurgy titanium alloys for orthopedic and dental applications. The influence of the hot isostatic pressing (HIP) post-processing step on structural and phase changes, porosity healing, and mechanical strength in a powder metallurgy Ti35Nb2Sn alloy was studied. Powders were pressed at room temperature at 750 MPa, and then sintered at 1350 °C in a vacuum for 3 h. The standard HIP process at 1200 °C and 150 MPa for 3 h was performed to study its effect on a Ti35Nb2Sn powder metallurgy alloy. The influence of the HIP process and cold rate on the density, microstructure, quantity of interstitial elements, mechanical strength, and Young’s modulus was investigated. HIP post-processing for 2 h at 1200 °C and 150 MPa led to greater porosity reduction and a marked retention of the β phase at room temperature. The slow cooling rate during the HIP process affected phase stability, with a large amount of α”-phase precipitate, which decreased the titanium alloy’s yield strength.

scholarly journals Study on the erosion of Mo/ZrO2 alloys in glass melting process

2020 ◽  
Vol 39 (1) ◽  
pp. 595-598
Author(s):  
Cui Chaopeng ◽  
Zhu Xiangwei ◽  
Li Qiang ◽  
Zhang Min ◽  
Zhu Guangping
Keyword(s):  
Grain Size ◽  
Corrosion Resistance ◽  
Powder Metallurgy ◽  
Hydrothermal Synthesis ◽  
Grain Boundaries ◽  
Electrode Material ◽  
Glass Melting ◽  
Melting Process ◽  
Fine Grain ◽  
Conventional Electrode

AbstractThe Mo/ZrO2 electrode was prepared by combining hydrothermal synthesis with powder metallurgy, and this new electrode material has a totally different microstructure from the conventional electrode. The grain size of the new electrode was fine, and the size of ZrO2 in the alloy reached 200 nm. According to the results, the Mo–ZrO2 electrode has better performance, because the erosion occurs along the grain boundaries. Meanwhile, the new electrode, based on its fine grain, can effectively improve the corrosion resistance of the electrode.

TECHNOLOGICAL WAYS TO CREATE COMPOSITE MATERIALS BASED ON HEAT-RESISTANT REFRACTORY COMPOUNDS (review)

2021 ◽  
pp. 12-20
Author(s):  
A.V. Shestakov ◽  
◽  
M.M. Karashaev ◽  
N.S. Dmitriev ◽  
◽  
...  
Keyword(s):  
Composite Materials ◽  
Powder Metallurgy ◽  
Thermomechanical Processing ◽  
Technological Plasticity ◽  
Heat Resistant ◽  
System A ◽  
Refractory Compounds ◽  
Similar Materials ◽  
Powder Metallurgy Methods ◽  
Rocket Technology

The article discusses the main technological approaches to obtain heat-resistant and heat-resistant materials based on compounds in the Ni–Al system in order to use them in promising products of aviation and rocket technology. It is shown that when receiving materials based on compounds in the Ni-Al system, a phase of eutectic origin is formed based on the Ni3Al compound, which reduces the technological plasticity of the alloys of this system. The use of powder metallurgy methods eliminates such phases in the structure of alloys obtained using granule metallurgy technology, as well as with the use of special methods of powder metallurgy. Technological approaches are presented to obtain similar materials using powder metallurgy methods combined with thermomechanical processing.

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