Effect of the particle size distribution on physical properties, composition, and quality of gas atomized Astroloy powders for HIP application

Bassini, Emilio; Napal, Unai Galech; Biurrun, Tomas Soria; Aristizabal, M.; Iturriza, I.; Biamino, Sara; Ugues, Daniele

doi:10.1016/j.jallcom.2021.161631

Cited by 14 publications

(5 citation statements)

References 23 publications

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“…Rapid heat transfer occurs in fine droplets, whereas heat transfer is comparatively sluggish for coarser droplets. Therefore, the droplet size is directly related to its cooling rate, which, in turn, influences the solidification microstructure [25]. Generally, there is a limited solute redistribution in front of the solid-liquid interface under high cooling rates.…”

Section: Effect Of Cooling Rate On Microstructural Evolution Of Alfe9...mentioning

confidence: 99%

Deciphering Microstructures and Phases of Gas-Atomised Novel Al-Fe-Si-Cr-Ni Alloys

Bhatt,

Martucci,

Virgillito

et al. 2023

Metals

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Rapid solidification techniques, such as gas atomisation, have been widely implemented in metallic alloys/composites to increase solid solubility, avoid or mitigate segregation phenomena, and favour metastable phase formation to enhance performance. Particularly, gas atomisation can enhance the solid solubility of low diffusion coefficient elements like Fe, Ni, Mn, Zr, and Cr in the α-Al matrix, yielding metastable phases. As a result, Al alloys exhibit excellent strength at high temperatures. In this study, the AISI 304L alloy was employed to introduce Fe, Ni, and Cr elements into the AlSi10Mg alloy through gas atomisation, resulting in the formation of two distinct hypereutectic AlFe-based alloys: AlFe9Si8Cr2Ni and AlFe18Si8Cr5Ni2. Gas-atomised alloy powders were separated into different size fractions by sieving and characterised using X-ray diffraction, differential scanning calorimetry, optical microscopy, and scanning electron microscopy. Microstructural analyses revealed dendritic patterns with distinct phases, highlighting the influence of the alloying element content on the solidification processes. Furthermore, a synergic evaluation of the XRD and EDS analysis results allowed the identification of intermetallic phases and their distribution in the two systems.

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Section: Effect Of Cooling Rate On Microstructural Evolution Of Alfe9...mentioning

confidence: 99%

Deciphering Microstructures and Phases of Gas-Atomised Novel Al-Fe-Si-Cr-Ni Alloys

Bhatt,

Martucci,

Virgillito

et al. 2023

Metals

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show abstract

“…This is due to the laser measurement method, which tends to depress the small fraction count and expand the bigger ones due to the particle volume effect. The use of numeric PSD is then crucial because it is capable of detecting fine particles, which are responsible for changing the rheology of the powders and may also have the greatest amount of oxygen [33]. Furthermore, Figure 4 shows how the procedure for numeric PSD described in Section 2.1 is able to give more precise information on the particle population.…”

Section: Powders Characterizationmentioning

confidence: 99%

Parameters Optimization and Repeatability Study on Low-Weldable Nickel-Based Superalloy René 80 Processed via Laser Powder–Bed Fusion (L-PBF)

Martelli

Sivo

Calignano

et al. 2023

Metals

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This work aims to investigate the processability of René 80 via laser powder–bed fusion (L-PBF). René 80 is a poorly weldable Ni-superalloy, currently processed via investment casting to fabricate turbine blades working at an operating temperature of about 850 °C. The L-PBF parameters optimization aims to increase part integrity and enhance processing repeatability. This part was tackled by creating a complete design of experiments (DOE) in which laser power, scan speed and hatching distance were varied accordingly. Optimizing the abovementioned parameters minimized the crack density and pore area fraction. Hence, five parameter sets leading to a crack density lower than 100 µm/mm2 and a pore fraction between 0.045% and 0.085% were selected. Furthermore, the intra-print repeatability was studied by producing three specimens’ repetitions for each optimal set of parameters in the same build. The porosity value obtained was constant among repetitions, and the crack density (around 75 µm/mm2) had a slight standard deviation. The third step of the research assessed the inter-prints repeatability by producing a replica of the five selected parameter sets in a different build and by comparing the results with those studied previously. According to this latter study, the porosity fraction (ca. 0.06%) was constant in intra- and inter-print conditions. Conversely, crack density was lower than 100 µm/mm2 only in three sets of parameters, regardless of the intra- or inter-build cross-check. Finally, the best parameter set was chosen, emphasizing the average flaw fraction (least possible value) and repeatability. Once the optimal densification of the samples was achieved, the alloy’s microstructural features were also investigated.

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“…In the past, steel alloys were used as the main component of engines, but nowadays other alloys such as nickel base superalloys have gained prominence. Nickel superalloys are widely used due to their magnificent properties, even at extreme temperatures, which are provided by the high-volume fraction of gamma prime (γ ; Ni 3 (Al, Ti)) precipitates that is usually above the 50% of the alloy [1][2][3][4][5][6][7][8][9][10][11]. These alloys usually include other elements such as Cr, Co, Mo and W in order to reinforce the matrix.…”

Section: Introductionmentioning

confidence: 99%

“…of the alloy [1][2][3][4][5][6][7][8][9][10][11]. These alloys usually include other elements such as Cr, Co, Mo and W in order to reinforce the matrix.…”

Section: Introductionmentioning

confidence: 99%

Thermal Mass Effect on the Solution Cooling Rate and on HIPped Astroloy Component Properties

et al. 2022

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Astroloy is a Ni-based superalloy with high-volume fraction of γ′, which gives high temperature properties but reduces its forgeability. Therefore, powder metallurgy manufacturing processes such as Near Net Shape HIPping are the most suitable manufacturing technology for Astroloy. However, NNSHIP has its own drawbacks, such as the formation of prior particle boundaries (PPBs), which usually tend to decrease material mechanical properties. The detrimental effect of PPBs can be reduced by optimizing the entire HIP processing route. Conventional HIP cycles have very low cooling rates, especially in big components from industry, and thus a series of post-heat treatments must be applied in order to achieve desirable microstructures and improve the mechanical properties. Standard heat treatments for Astroloy are long and tedious with several steps of solutioning, stabilization and precipitation. In this work, two main studies have been performed. First, the effect of the cooling rate after the solutioning treatment, which is driven by the materials’ thermal mass, on the Astroloy microstructure and mechanical properties was studied. Experimental analyses and simulation techniques have been used in the present work and it has been found that higher cooling rates after solutioning increase the density of tertiary γ′ precipitates by 85%, and their size decreases by 22%, which leads to an increase in hardness from 356 to 372 HB30. This hardness difference tends to reduce after subsequent standard heat treatment (HT) that homogenizes the microstructure. The second study shows the effect of different heat treatments on the microstructure and hardness of samples with two different thermal masses (can and cube). More than double the density of γ′ precipitates was found in small cubes in comparison with cans with a higher thermal mass. Therefore, the hardness in cubes is between 4 and 20 HB 30 higher than in large cans, depending on the applied HT.

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Effect of the particle size distribution on physical properties, composition, and quality of gas atomized Astroloy powders for HIP application

Cited by 14 publications

References 23 publications

Deciphering Microstructures and Phases of Gas-Atomised Novel Al-Fe-Si-Cr-Ni Alloys

Deciphering Microstructures and Phases of Gas-Atomised Novel Al-Fe-Si-Cr-Ni Alloys

Parameters Optimization and Repeatability Study on Low-Weldable Nickel-Based Superalloy René 80 Processed via Laser Powder–Bed Fusion (L-PBF)

Thermal Mass Effect on the Solution Cooling Rate and on HIPped Astroloy Component Properties

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