scholarly journals Additive Manufacturing of Ti-48Al-2Cr-2Nb Alloy Using Gas Atomized and Mechanically Alloyed Plasma Spheroidized Powders

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3952
Author(s):  
Igor Polozov ◽  
Artem Kantyukov ◽  
Ivan Goncharov ◽  
Nikolay Razumov ◽  
Alexey Silin ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Relative Density ◽  
Tial Alloy ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Powder Bed ◽  
Β Phase ◽  
Preheating Temperature ◽  
Fine Microstructure ◽  
Temperature Scanning

In this paper, laser powder-bed fusion (L-PBF) additive manufacturing (AM) with a high-temperature inductive platform preheating was used to fabricate intermetallic TiAl-alloy samples. The gas atomized (GA) and mechanically alloyed plasma spheroidized (MAPS) powders of the Ti-48Al-2Cr-2Nb (at. %) alloy were used as the feedstock material. The effects of L-PBF process parameters—platform preheating temperature—on the relative density, microstructure, phase composition, and mechanical properties of printed material were evaluated. Crack-free intermetallic samples with a high relative density of 99.9% were fabricated using 900 °C preheating temperature. Scanning electron microscopy and X-Ray diffraction analyses revealed a very fine microstructure consisting of lamellar α2/γ colonies, equiaxed γ grains, and retained β phase. Compressive tests showed superior properties of AM material as compared to the conventional TiAl-alloy. However, increased oxygen content was detected in MAPS powder compared to GA powder (~1.1 wt. % and ~0.1 wt. %, respectively), which resulted in lower compressive strength and strain, but higher microhardness compared to the samples produced from GA powder.

scholarly journals An in-situ high-energy X-ray diffraction study on the hot-deformation behavior of a β-phase containing TiAl alloy

2013 ◽  
Vol 39 ◽  
pp. 25-33 ◽  
Author(s):  
T. Schmoelzer ◽  
K.-D. Liss ◽  
C. Kirchlechner ◽  
S. Mayer ◽  
A. Stark ◽  
...  
Keyword(s):  
Diffraction Study ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Tial Alloy ◽  
High Energy ◽  
X Ray Diffraction ◽  
Hot Deformation Behavior ◽  
X Ray ◽  
Β Phase

Investigation of mechanical properties and microstructures of GH536 fabricated by laser powder bed fusion additive manufacturing

2020 ◽  
Vol 235 (1-2) ◽  
pp. 155-165
Author(s):  
Yunpeng Ren ◽  
Heng Lu ◽  
Dongyang Xu ◽  
Yan Chen ◽  
Zhiduo Xin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Additive Manufacturing ◽  
Relative Density ◽  
Laser Energy ◽  
Hot Forging ◽  
Scanning Speed ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed

Laser powder bed fusion additive manufacturing of superalloys has received increasing attention in these years. In this article, the influence of parameters of laser powder bed fusion on mechanical properties and microstructures of nickel-based superalloy GH536 was investigated. Influence of laser power, scanning speed, hatch space and building direction on mechanical properties was discussed, and the optimal parameters were obtained. The relative density of samples fabricated by laser powder bed fusion could be as high as 99.5%. The processing window of laser energy density with 8.56 × 104–1.15 × 105 J/cm3 should be employed to make sure that the relative density is higher than 98%. The ultimate tensile strength and yield stress of GH536 sample made by laser powder bed fusion were 950 and 606 MPa, respectively, which were superior to samples with the tensile strength of 767 MPa and yield strength of 379 MPa prepared by traditional hot forging method. The hardness of the sample could reach 316.8 HV.

scholarly journals Solid-State Phase Transformations in Thermally Treated Ti–6Al–4V Alloy Fabricated via Laser Powder Bed Fusion

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2876
Author(s):  
Paolo Mengucci ◽  
Eleonora Santecchia ◽  
Andrea Gatto ◽  
Elena Bassoli ◽  
Antonella Sola ◽  
...  
Keyword(s):  
Solid State ◽  
Phase Transformations ◽  
Xrd Analysis ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
X Ray Diffraction ◽  
Powder Bed ◽  
Β Phase ◽  
Transmission Electron ◽  
Scanning Transmission

Laser Powder Bed Fusion (LPBF) technology was used to produce samples based on the Ti–6Al–4V alloy for biomedical applications. Solid-state phase transformations induced by thermal treatments were studied by neutron diffraction (ND), X-ray diffraction (XRD), scanning transmission electron microscopy (STEM) and energy-dispersive spectroscopy (EDS). Although, ND analysis is rather uncommon in such studies, this technique allowed evidencing the presence of retained β in α’ martensite of the as-produced (#AP) sample. The retained β was not detectable by XRD analysis, nor by STEM observations. Martensite contains a high number of defects, mainly dislocations, that anneal during the thermal treatment. Element diffusion and partitioning are the main mechanisms in the α ↔ β transformation that causes lattice expansion during heating and determines the final shape and size of phases. The retained β phase plays a key role in the α’ → β transformation kinetics.

Fine Microstructure of a Mechanically Alloyed Oxide Dispersion Strengthened Nickel-Base Superalloy

1977 ◽  
Vol 35 ◽  
pp. 298-299
Author(s):  
Jordi Marti ◽  
Timothy E. Howson ◽  
David Kratz ◽  
John K. Tien
Keyword(s):  
Solid Solution ◽  
Volume Fraction ◽  
Stress Rupture ◽  
Oxide Dispersion Strengthened ◽  
Solid Solution Alloy ◽  
Oxide Dispersion ◽  
Creep And Stress Rupture ◽  
Mechanically Alloyed ◽  
Fine Microstructure ◽  
Nickel Base

The previous paper briefly described the fine microstructure of a mechanically alloyed oxide dispersion strengthened nickel-base solid solution. This note examines the fine microstructure of another mechanically alloyed system. This alloy differs from the one described previously in that it is more generously endowed with coherent precipitate γ forming elements A1 and Ti and it contains a higher volume fraction of the finely dispersed Y2O3 oxide. An interesting question to answer in the comparative study of the creep and stress rupture of these two ODS systems is the role of the precipitate γ' in the mechanisms of creep and stress rupture in alloys already containing oxide dispersoids.The nominal chemical composition of this alloy is Ni - 20%Cr - 2.5%Ti - 1.5% A1 - 1.3%Y203 by weight. The system receives a three stage heat treatment-- the first designed to produce a coarse grain structure similar to the solid solution alloy but with a smaller grain aspect ratio of about ten.

Mechanical Alloying Behavior in the Nb-Si, Ta-Si, and Nb-Ta-Si Systems

1988 ◽  
Vol 133 ◽  
Author(s):  
K. S. Kumar ◽  
S. K. Mannan
Keyword(s):  
High Temperature ◽  
Mechanical Alloying ◽  
Mechanical Milling ◽  
Room Temperature ◽  
Crystalline Compound ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Α Phase

ABSTRACTThe mechanical alloying behavior of elemental powders in the Nb-Si, Ta-Si, and Nb-Ta-Si systems was examined via X-ray diffraction. The line compounds NbSi2 and TaSi2 form as crystalline compounds rather than amorphous products, but Nb5Si3 and Ta5Si3, although chemically analogous, respond very differently to mechanical milling. The Ta5Si3 composition goes directly from elemental powders to an amorphous product, whereas Nb5Si3 forms as a crystalline compound. The Nb5Si3 compound consists of both the tetragonal room-temperature α phase (c/a = 1.8) and the tetragonal high-temperature β phase (c/a = 0.5). Substituting increasing amounts of Ta for Nb in Nb5Si3 initially stabilizes the α-Nb5Si3 structure preferentially, and subsequently inhibits the formation of a crystalline compound.

Multi-material model for the simulation of powder bed fusion additive manufacturing

2021 ◽  
Vol 194 ◽  
pp. 110415
Author(s):  
Vera E. Küng ◽  
Robert Scherr ◽  
Matthias Markl ◽  
Carolin Körner
Keyword(s):  
Additive Manufacturing ◽  
Material Model ◽  
Powder Bed Fusion ◽  
Powder Bed

scholarly journals Comparison of Phase Characteristics and Residual Stresses in Ti-6Al-4V Alloy Manufactured by Laser Powder Bed Fusion (L-PBF) and Electron Beam Powder Bed Fusion (EB-PBF) Techniques

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 796
Author(s):  
Aya Takase ◽  
Takuya Ishimoto ◽  
Naotaka Morita ◽  
Naoko Ikeo ◽  
Takayoshi Nakano
Keyword(s):  
Electron Beam ◽  
Residual Stresses ◽  
Cooling Rate ◽  
Process Parameters ◽  
Phase Evolution ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Solidification Temperature ◽  
Powder Bed ◽  
Β Phase

Ti-6Al-4V alloy fabricated by laser powder bed fusion (L-PBF) and electron beam powder bed fusion (EB-PBF) techniques have been studied for applications ranging from medicine to aviation. The fabrication technique is often selected based on the part size and fabrication speed, while less attention is paid to the differences in the physicochemical properties. Especially, the relationship between the evolution of α, α’, and β phases in as-grown parts and the fabrication techniques is unclear. This work systematically and quantitatively investigates how L-PBF and EB-PBF and their process parameters affect the phase evolution of Ti-6Al-4V and residual stresses in the final parts. This is the first report demonstrating the correlations among measured parameters, indicating the lattice strain reduces, and c/a increases, shifting from an α’ to α+β or α structure as the crystallite size of the α or α’ phase increases. The experimental results combined with heat-transfer simulation indicate the cooling rate near the β transus temperature dictates the resulting phase characteristics, whereas the residual stress depends on the cooling rate immediately below the solidification temperature. This study provides new insights into the previously unknown differences in the α, α’, and β phase evolution between L-PBF and EB-PBF and their process parameters.

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