Thermal flow characteristics and the evolution of laser absorption in laser powder bed fusion of Cu-Cr-Zr alloy

This study shows a rapid and systematic approach towards identifying full density and peak hardness for an Al-Mg-Sc-Zr alloy commonly known as Scalmalloy®. The alloy is tailored for the laser powder bed fusion process and has been shown to be printable with >99.8% relative density. The microstructure suggests Al grain refinement in melt pool boundaries, associated with formation of primary Al3(Sc,Zr) particles during solidification. Peak hardening response was identified by heat treatment tests at 573,598 and 623 K between 0 and 10 h. A peak hardness of 172 HV0.3 at 598 K for 4 h was identified. The mechanical properties were also tested with yield and ultimate strengths of 287 MPa and 364 MPa in as-printed and 468 MPa and 517 MPa in peak hardened conditions, respectively, which is consistent with the literature. Such an approach is considered apt when qualifying new materials in industrial laser powder bed fusion systems. The second part of the study discusses the thermal stability of such alloys post-peak-hardening. One set of samples was peak hardened at the conditions identified before and underwent secondary ageing at three different temperatures of 423,473 and 523 K between 0 and 120 h to understand thermal stability and benchmark against conventional Al alloys. The secondary heat treatments performed at lower temperatures revealed lower deterioration of hardness over ageing times as compared to the datasheets for conventional Al alloys and Scalmalloy®, thus suggesting that longer ageing times are needed.

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Influence of the Zr content on the processability of a high strength Al-Zn-Mg-Cu-Zr alloy by laser powder bed fusion

Materials Characterization ◽

10.1016/j.matchar.2021.111650 ◽

2021 ◽

pp. 111650

Author(s):

A. Martin ◽

M. Vilanova ◽

E. Gil ◽

M. San Sebastian ◽

C.Y. Wang ◽

...

Keyword(s):

High Strength ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

Zr Alloy

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Effects of powder reuse on the microstructure and mechanical behaviour of Al–Mg–Sc–Zr alloy processed by laser powder bed fusion (LPBF)

Additive Manufacturing ◽

10.1016/j.addma.2020.101625 ◽

2020 ◽

Vol 36 ◽

pp. 101625

Author(s):

Laura Cordova ◽

Ton Bor ◽

Marc de Smit ◽

Simone Carmignato ◽

Mónica Campos ◽

...

Keyword(s):

Mechanical Behaviour ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

Zr Alloy

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Preparation of Cu-Cr-Zr Alloy by Laser Powder Bed Fusion: Parameter Optimization, Microstructure, Mechanical and Thermal Properties for Microelectronic Applications

Metals ◽

10.3390/met11091410 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1410

Author(s):

Xiangyao Fang ◽

Weisheng Xia ◽

Qingsong Wei ◽

Yiping Wu ◽

Weiwen Lv ◽

...

Keyword(s):

Heat Transfer ◽

Thermal Properties ◽

Vickers Hardness ◽

Heat Dissipation ◽

Phase Identification ◽

Mechanical And Thermal Properties ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

Zr Alloy

Laser powder bed fusion (LPBF) technology is beneficial for the fabrication of thermal conductive materials, integrating with the predesigned structure, which shows a great potential for high heat dissipation applications. Here, a Cu–Cr–Zr alloy with relative density of 98.53% is successfully prepared by LPBF after process optimization. On this basis, microstructure, phase identification, precipitates, mechanical and thermal properties are investigated. The results demonstrate that the surface morphology of microstructure is affected by laser energy density, the α-Cu is the main phase of the LPBF sample and the virgin powder, the size of Cr spherical precipitates in some areas is about 1 μm, and the tensile fracture mode is a mixed ductile–brittle mode. Furthermore, the Vickers hardness of the LPBF Cu-Cr-Zr sample is 70.7 HV to 106.1 HV, which is higher than that of LPBF Cu and a wrought C11000 Cu, and the difference in Vickers hardness of different planes reflects the anisotropy. Ultimately, the two types of Cu–Cr–Zr alloy heat sinks are successfully fabricated, and their heat transfer coefficients are positively correlated with the volume flow. The heat dissipation performance of the cylindrical micro-needle heat sink is better, and its maximum heat transfer coefficient is 3887 W/(m2·K).

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The Effect of Powder Characteristics on Build Quality of High-Purity Tungsten Produced via Laser Powder Bed Fusion (LPBF)

Metallurgical and Materials Transactions A ◽

10.1007/s11661-019-05601-6 ◽

2020 ◽

Vol 51 (3) ◽

pp. 1367-1378 ◽

Cited By ~ 2

Author(s):

A. C. Field ◽

L. N. Carter ◽

N. J. E. Adkins ◽

M. M. Attallah ◽

M. J. Gorley ◽

...

Keyword(s):

Size Distribution ◽

High Purity ◽

Flow Characteristics ◽

Theoretical Density ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

Substrate Plate ◽

Power Densities ◽

Spheroidized Powder

AbstractTwo high-purity tungsten powders, produced via different manufacturing techniques, were characterized to determine size distribution, morphology, thermal properties, and flow characteristics and, thus, the likely suitability for Laser Powder Bed Fusion (LPBF) production. Specimens from duplicate builds were produced with the two powders and characterized for density, defect mechanisms, and thermal penetration into the substrate plate to compare apparent power densities. The first powder was a chemically reduced powder with irregular morphology and the second, a plasma spheroidized powder with highly spherical morphology. The latter was found to have tighter morphological control and size distribution, having a third of particles at the modal particle size in comparison to a fifth of the chemically reduced powder. This led to better flow characteristics, and an increase of 1.5 g cm−3 (1500 kg m−3) in the packing densities seen in the powder bed which corresponds to 57 pct theoretical density vs 50 pct theoretical density in the chemically reduced powder. As a result, the specimens produced from the plasma spheroidized powder had higher densities (97.3 vs 88.5 pct) and the dominant defect mechanism moved from lack of fusion dominated in the chemically reduced powder to cracking dominated in the plasma spheroidized. The plasma spheroidized powder also showed higher apparent power densities (effective absorptivities) as evidenced by an 80 pct deeper penetration of the laser into the substrate plate.

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Evaluation of Inconel 718 Metallic Powder to Optimize the Reuse of Powder and to Improve the Performance and Sustainability of the Laser Powder Bed Fusion (LPBF) Process

Materials ◽

10.3390/ma14061538 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1538

Author(s):

Konrad Gruber ◽

Irina Smolina ◽

Marcin Kasprowicz ◽

Tomasz Kurzynowski

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Inconel 718 ◽

Chemical Properties ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

Laser Absorption ◽

Multiple Uses

In this paper, a detailed assessment of Inconel 718 powder, with varying degrees of degradation due to repeated use in the Laser Powder Bed Fusion (LPBF) process, has been undertaken. Four states of IN718 powder (virgin, used, overflow and spatter) were characterized in terms of their morphology, flowability and physico-chemical properties. Studies showed that used and overflow powders were almost identical. The fine particle-size distribution of the virgin powder, in which 50% of particles were found to be below the nominal particle-size distribution (PSD), was recognized as the main reason for its lower flowability and the main cause of the differentiation between virgin, used and overflow powders. Only spatter powder was found to be degraded enough to preclude its direct LPBF reuse. The oxygen content in the spatter powder exceeded the limit value for IN718 by 290 ppm, and aluminum oxide spots were found on the spatter particles surfaces. Laser absorption analysis showed 10 pp higher laser absorption compared to the other powders. The results of evaluation showed that IN718 powder is resistant to multiple uses in the LPBF process. Due to the low degradation rate of IN718 powder, overflow powder can be re-enabled for multiple uses with a proper recycling strategy.

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New Aluminum Alloys Specifically Designed for Laser Powder Bed Fusion: A Review

Materials ◽

10.3390/ma12071007 ◽

2019 ◽

Vol 12 (7) ◽

pp. 1007 ◽

Cited By ~ 25

Author(s):

Alberta Aversa ◽

Giulio Marchese ◽

Abdollah Saboori ◽

Emilio Bassini ◽

Diego Manfredi ◽

...

Keyword(s):

Aluminum Alloys ◽

State Of The Art ◽

Complex Geometries ◽

Low Density ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

Laser Absorption ◽

Powder Flowability ◽

Am Processes

Aluminum alloys are key materials in additive manufacturing (AM) technologies thanks to their low density that, coupled with the possibility to create complex geometries of these innovative processes, can be exploited for several applications in aerospace and automotive fields. The AM process of these alloys had to face many challenges because, due to their low laser absorption, high thermal conductivity and reduced powder flowability, they are characterized by poor processability. Nowadays mainly Al-Si alloys are processed, however, in recent years many efforts have been carried out in developing new compositions specifically designed for laser based powder bed AM processes. This paper reviews the state of the art of the aluminum alloys used in the laser powder bed fusion process, together with the microstructural and mechanical characterizations.

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