“…Meanwhile, it is obvious that the scan track consists of columnar grains, while the boundary of the scan track consists of equiaxed grains owing to the Gaussian distribution of the laser energy. [29] When scanning the powder bed, the rapidly moving laser beam weakens the temperature gradient in the scan track. The cooling rate in the middle of the scan track is the highest compared to that of the surrounding regions and gradually decreases towards the boundary.…”
Section: B Phase Analysismentioning
confidence: 99%
“…[23] Joseph et al prepared an AlxCoCrFeNi alloy by laser deposition, which showed a significant asymmetry of tensile/compression. [24,25] Since then, different series of HEAs, such as FeMnCoCrNi, [26][27][28][29] AlCoCrFeNi, [30] AlCrCuFeNi, [31] AlCoCuFeNi, [32] and CoCrFeNiTi, [33] have been successfully fabricated using AM. Unfortunately, although the CoCrNi MEA has excellent mechanical properties, few studies have been done on the AM process for such alloys till now.…”
Additive manufacturing of an equimolar CoCrNi medium entropy alloy (MEA) by selective laser melting (SLM) was investigated, emphasizing its microstructure, properties, and metallurgical defects. It was found that SLM sample density exhibited a non-monotonic relation with their volume energy density (VED); the density first increased but then decreased while the input VED was gradually increasing. A maximal relative density of 98.9 pct was accessible at a VED of 83.3 J/mm 3. X-ray diffraction indicated that the printed CoCrNi MEA exhibited an FCC single-crystal structure where the lattice constant decreased with the increasing VED owing to the evaporation of the Cr element in the SLM process. The average grain size gradually increased with increasing VED, irrespective of whether viewed from the top or the side of the printed part. Similarly, the residual stress increased with increasing VED, which produced more microcracks and deteriorated the tensile preformation of the printed samples, although the yield strength (630 MPa) showed no apparent difference at different VEDs. Owing to the ultrafine cell structure, the mechanical property of the SLM printed sample was twice that of cast or wrought CoCrNi MEA.
“…Meanwhile, it is obvious that the scan track consists of columnar grains, while the boundary of the scan track consists of equiaxed grains owing to the Gaussian distribution of the laser energy. [29] When scanning the powder bed, the rapidly moving laser beam weakens the temperature gradient in the scan track. The cooling rate in the middle of the scan track is the highest compared to that of the surrounding regions and gradually decreases towards the boundary.…”
Section: B Phase Analysismentioning
confidence: 99%
“…[23] Joseph et al prepared an AlxCoCrFeNi alloy by laser deposition, which showed a significant asymmetry of tensile/compression. [24,25] Since then, different series of HEAs, such as FeMnCoCrNi, [26][27][28][29] AlCoCrFeNi, [30] AlCrCuFeNi, [31] AlCoCuFeNi, [32] and CoCrFeNiTi, [33] have been successfully fabricated using AM. Unfortunately, although the CoCrNi MEA has excellent mechanical properties, few studies have been done on the AM process for such alloys till now.…”
Additive manufacturing of an equimolar CoCrNi medium entropy alloy (MEA) by selective laser melting (SLM) was investigated, emphasizing its microstructure, properties, and metallurgical defects. It was found that SLM sample density exhibited a non-monotonic relation with their volume energy density (VED); the density first increased but then decreased while the input VED was gradually increasing. A maximal relative density of 98.9 pct was accessible at a VED of 83.3 J/mm 3. X-ray diffraction indicated that the printed CoCrNi MEA exhibited an FCC single-crystal structure where the lattice constant decreased with the increasing VED owing to the evaporation of the Cr element in the SLM process. The average grain size gradually increased with increasing VED, irrespective of whether viewed from the top or the side of the printed part. Similarly, the residual stress increased with increasing VED, which produced more microcracks and deteriorated the tensile preformation of the printed samples, although the yield strength (630 MPa) showed no apparent difference at different VEDs. Owing to the ultrafine cell structure, the mechanical property of the SLM printed sample was twice that of cast or wrought CoCrNi MEA.
“…[110,120,137] In particular, with DED, it was found that the number of layers being deposited had an impact on grain structure (changing from equiaxed to columnar as the number of layers increases). [110,120,137] In particular, with DED, it was found that the number of layers being deposited had an impact on grain structure (changing from equiaxed to columnar as the number of layers increases).…”
Section: Materials Propertiesmentioning
confidence: 99%
“…Tensile stress–strain curves of direct laser‐deposited Al‐5Si‐1Cu‐Mg alloy. Reproduced with permission . Copyright 2019, Elsevier.…”
Section: Am Technology Backgroundmentioning
confidence: 99%
“…For DLD, the relationship between process parameters and properties has also been studied . In particular, with DED, it was found that the number of layers being deposited had an impact on grain structure (changing from equiaxed to columnar as the number of layers increases) . This in turn resulted in a change in mechanical properties as shown in Figure , where the near‐equiaxed structure exhibits higher ductility but lower strength.…”
Additive manufacturing (AM) is a transformative technology that has rapidly grown over the past decade. AM processes build parts layer by layer and have found applications in the aerospace, biomedical, and automotive fields. The technology holds particular promise for the aerospace industry due to the reduced process time, weight savings of parts, and opportunities for new material development. Herein, a review of laser-based AM processes, existing AM systems, and aerospace parts being fabricated is presented. It further explores the material properties and microstructure of printed samples with both powder bed fusion and direct energy deposition processes. The benefits and challenges associated with the widespread use of the technology are discussed with emphases on the aerospace sector. Finally, the steps required for parts produced by AM processes to become certified for use in aerospace applications are presented.
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