Influence of the Feed Powder Composition in Mechanical Properties of AlN-Nano-Reinforced Aluminium Composites Coatings Deposited by Reactive Direct Laser Deposition

Ainhoa Riquelme,María Dolores Escalera-Rodriguez,Pilar Rodrigo,Pablo García-Fogeda,Joaquín Rams

doi:10.3390/met10070926

Ainhoa Riquelme, María Dolores Escalera-Rodriguez + Show 3 more

Open Access

https://doi.org/10.3390/met10070926

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Abstract

Aluminium matrix composite coatings reinforced with AlN nanopaticles have been manufactured by direct laser deposition on an AA6082 alloy substrate. The reinforcement of the composite has been generated by the direct nitridation reaction of the feed powder with the carrier gas (N2) heated by an HPDL beam during the fabrication of the coating. The coating obtained consists of nano-sized AlN particles in an aluminium matrix, and the crystalline structure of the obtained AlN depends on the characteristics of the powder used. In this work, the influence of the feed powder composition is studied by comparison among pure aluminium, Al12-Si alloy, and AA6061 alloy, on the formation of AlN and its crystalline structure. A correlation was established between the temperature distribution reached by the particles, their composition, and the nitridation reaction mechanisms. The effect of the reinforcement was evaluated by comparing the microstructure and mechanical properties (microhardness, nanoindentation) of the composite costing with non-reinforced Al coatings and uncoated AA6082. Al/AlN composite coatings with improved properties were achieved, reaching hardness values that were 65% higher than coatings without reinforcement.

Highlights

Improving the efficiency of the means of transport in order to reduce fuel consumption and pollution is currently one of the main challenges that the transport industries are facing
Mrówka-Nowotnik et al [1] identified all the intermetallic phases formed in 6082 alumnium alloy casting, and Birol [2] investigated the effect of ageing treatments T5 and T6 on the final properties of AA6082 alloy; they found that the quench is the most critical processing parameter
In this work, we propose a novel process based on the formation of an aluminium alloy composite reinforced with AlN particles by the in situ reaction between an aluminium alloy and nitrogen under the irradiation of the laser used during Direct Laser Deposition (DLD), so that the composite is formed while the composite is being deposited

Summary

Introduction

Improving the efficiency of the means of transport in order to reduce fuel consumption and pollution is currently one of the main challenges that the transport industries are facing. In this work, we propose a novel process based on the formation of an aluminium alloy composite reinforced with AlN particles by the in situ reaction between an aluminium alloy and nitrogen under the irradiation of the laser used during DLD, so that the composite is formed while the composite is being deposited This is an innovative process that can be afterwards applied on other additive manufacturing processes, and this study shows that the surface properties obtained largely exceed those of the alloys conventionally used in the automotive and aerospace industries. Nanoindentation maps have identified the hardening effect of the particles in the matrix

Materials and Methods

Initial Powder Characteristics

Laser Treated

Discussion

N2 with