On the Possible Mechanisms of Porosity Formation during Laser Melt Injection (LMI) Technology

Buza, Gábor; Janó, Viktória; Svéda, Mária; Verezub, Olga; Kálazi, Zoltán; Kaptay, George; Roósz, András

doi:10.4028/www.scientific.net/msf.589.79

Cited by 17 publications

(4 citation statements)

References 4 publications

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“…[13]. In particular, this phenomenon can occur during laser cladding of Nibased alloys on Cu substrate since the process involves a very high solidification rate (due to the high thermal conductivity of Cu).…”

Section: Porosity Measurementmentioning

confidence: 98%

Laser cladding of nickel-based alloy coatings on copper substrates

Balu

Rea

Deng³

2015

SPIE Proceedings

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The wear resistance of high-value copper components used in the metal casting, automotive, aerospace and electrical equipment industries can be improved by applying nickel (Ni)-based coatings through laser cladding. A high-power diode laser array providing continuous power levels up to 10 kilowatts with beam-shaping optics providing a rectangular focal region of various dimensions was used to deposit Ni-based alloy coatings with controlled thickness ranging from 0.3 mm to 1.6 mm in a single pass on copper (Cu) substrates. Slotted powder feeding plates with various discrete widths delivered uniform streams of powdered metal particles entrained in a carrier gas, matching the selected focal spot dimensions. To enhance laser beam coupling with the substrate and to avoid defects such as cracks, delamination and porosity, Cu substrates were preheated to a temperature of 300°C. The effect of heat input on microstructure of the cladding and extent of the heat-affected zone (HAZ) was evaluated using optical microscopy and scanning electron microscopy. Excessive heat input with longer interaction time increased dilution, porosity and expanded HAZ that significantly reduced the hardness of both the clad and the Cu substrates. Average microhardness of the Ni-C-B-Si-W alloy coating was 572 HV, which was almost 7 times greater than the hardness of the Cu substrate (84 HV). IntroductionCopper (Cu) and its alloys are widely used in metal casting, marine, automotive and electrical equipment industries due to a combination of very high conductivity (both thermal and electrical) and good corrosion resistance. However, these materials are not good candidates for applications involving casting and rolling that demand both high wear resistance and good thermal conductivity, because of their low hardness and poor tribological properties. In order to enhance the wear resistance of Cu-based material in such applications, it is common practice to coat nickel (Ni)-based high performance materials using various techniques such as chemical plating, electro-plating, plasma transferred arc (PTA), thermal spray and laser cladding (LC). Among these techniques, both PTA and LC are capable of producing a metallurgical bond between the substrate and coating. It is reported [1] that PTA can produce thicker metal deposits with lower production costs than LC. However, the development of cost-effective, high-power direct diode laser-based cladding capable of producing deposition rates up to 30 lb/hr now makes LC competitive with PTA. Furthermore, LC with a high-power direct diode laser offers controlled heat input with increased throughput (via large-area cladding) and good wall-plug efficiency resulting in overall cost reduction when fabricating high-performance coatings.Cu-based alloys are generally excellent reflectors and poor absorbers of visible and near-infrared light, which is typically not favorable for laser processing. The variation of the room-temperature optical absorption with wavelength for Cu and Ni is shown in Figure 1. A sharp drop in...

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Section: Porosity Measurementmentioning

confidence: 98%

Laser cladding of nickel-based alloy coatings on copper substrates

Balu

Rea

Deng³

2015

SPIE Proceedings

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“…The gas porosity in the DED components is primarily a result of the entrapped gases that fail to escape from the melt pool before it solidifies (Figure 2(b) [93]). The sources of such gases are those within the original powders [44,91], shielding gases [93,95,100], and vapours of the constituent alloying elements [88,101]. Powders prepared through gas atomization may also contain small gas pores filled with argon or nitrogen due to gas entrapment [44,91].…”

Section: Structures Of the Ded-processed Alloysmentioning

confidence: 99%

Directed energy deposition of metals: processing, microstructures, and mechanical properties

Kumar

Chandra

et al. 2022

International Materials Reviews

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Amongst the many additive manufacturing (AM) techniques, directed energy deposition (DED) is a prominent one, which can also be used for the repair of damaged components. In this paper, we provide an overview on it, with emphasis on the typical microstructures of DED alloys and discuss the processing-microstructure-mechanical property correlations. Comparison is made with those manufactured using the conventional techniques and those obtained with laser beam powder bed fusion (LB-PBF). The characteristic solidification rates and thermal histories in DED result in distinct micro-and meso-structural features and mechanical performance, which are succinctly summarized. The potential of DED for manufacturing graded materials and for component repair is elaborated while highlighting the key-associated challenges and possible solutions. Modelling and simulation studies that facilitate an in-depth understanding of the DED technique are summarized. Finally, some critical issues and research directions that would help develop DED further and extend its application potential are identified.

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“…In this method, the right size of the metal powder particles and the right gas velocity must be used, otherwise the unreacted particles and pores may occur in the modified layer. 11,23 Moreover, grains of the injected metal powder are usually covered with a thin oxide layer, which may cause a decrease in the properties of the layer produced. 23 When a powder paste or slurry is used, the bonding agent may burn during melting, and this may lead to pore formation.…”

Section: Introductionmentioning

confidence: 99%

“…11,23 Moreover, grains of the injected metal powder are usually covered with a thin oxide layer, which may cause a decrease in the properties of the layer produced. 23 When a powder paste or slurry is used, the bonding agent may burn during melting, and this may lead to pore formation.…”

Section: Introductionmentioning

confidence: 99%

Properties of Mg laser alloyed with Al or AlSi20

Mola

Dziadoń

Jagielska-Wiaderek

2016

Surface Engineering

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The alloyed surface layers were produced using thin Al or AlSi20 plates, which were first diffusion bonded and then melted into the Mg substrate. The microscopic analysis showed that alloying with Al led to the formation of an Al-enriched surface layer containing a high volume fraction of an Mg 17 Al 12 phase. Applying AlSi20, on the other hand, resulted in the formation of an Al/Sienriched layer containing Mg 2 Si, Mg 2 Al 3 and Mg 17 Al 12 phases. The experimental results indicate that surface alloying of Mg with Al or AlSi20 using the presented method improved the properties of the material. The microhardness of the Al-and Al/Si-enriched layers was much higher than that of the substrate. Higher wear resistance was observed for the Al/Si-enriched layer. The alloyed layers provided a certain level of protection of Mg against corrosion. The specimens alloyed with Al showed better anticorrosive properties than those alloyed with AlSi20.

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On the Possible Mechanisms of Porosity Formation during Laser Melt Injection (LMI) Technology

Cited by 17 publications

References 4 publications

Laser cladding of nickel-based alloy coatings on copper substrates

Laser cladding of nickel-based alloy coatings on copper substrates

Directed energy deposition of metals: processing, microstructures, and mechanical properties

Properties of Mg laser alloyed with Al or AlSi20

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