Properties and characterization of an aluminium–silicon nitride fibre powder metal composite

Abstract

In this article, we fabricated one-dimensional 0.5 vol% silicon nitride (Si 3 N 4) fibre reinforced Alumix123 matrix composites by the powder metallurgy method. Si 3 N 4 is a ceramic material with high strength, stiffness and low coefficient of thermal expansion. The Si 3 N 4 used in the study is comprised of single crystal fibres with sub-micrometre diameter and length < 25 μm. The size of the fibre is smaller than the metal matrix powder allowing it to coat the metal powder before consolidation rather than forming agglomerations that might lead to pores and poor mechanical properties. We investigated the effects of Si 3 N 4 fibre additions on the densification, hardness, elastic modulus and tensile strength. The experimental results found that the Si 3 N 4 fibre effectively enhanced the mechanical properties of the composites at low additions. The microstructural analysis clearly shows the Si 3 N 4 fibres in the sintered grain boundaries. The interface between the fibre and the Alumix123 matrix showed good wetting and bonding with only minimal reaction. The Si 3 N 4 fibre reinforced Alumix123 composites have potential uses in the automobile and aerospace industries due to their improved specific mechanical properties.

Selective laser melting of stainless steel and silicon nitride fibre metal matrix composites

“…A full characterisation has been previously reported by one of the authors. 38 The Si 3 N 4 filler fibres are attached to the base metal particles by proprietary mechanical blending at Nuenz. Si 3 N 4 was added to 316L at 1 vol%, which was determined to be the maximum surface loading for fibres based on studies previously carried out using aluminium powder.…”

Characteristics of six layered Al/Si3N4 functionally graded materials prepared through two-step pressureless sintering process

“…As the density of the sample increased, the porosity in Al/Si3N4 FGM sample was reduced to 8.74% after sintering. The decrease in porosity of the FGM may be attributed to the high sintering temperature of 620 ºC as well as uniform dispersion of reinforcement [4]. journal.ump.edu.my/jmes ◄…”

“…Hardness is a representative material property for other mechanical properties. It directly affects the toughness and strength, besides can be a good indication for the estimation of the wear resistance of the material [4]. Figure 9 shows the distribution of Vickers microhardness results along the thickness of Al/Si3N4 FGM sample.…”

“…The AMMCs have an apparent advantage in terms of the economic perspective as Al is less expensive compared to other lightweight structural metals, for example magnesium, Mg and titanium, Ti [2]. The reinforcement phases for AMMC are usually composed of ceramic constituents either in the form of particles [3], fibres [4] or whiskers [2]. AMMC can be tailored into Functionally Graded Materials (FGM) structures comprising of metal and ceramic layers combined through spatial gradation of each constituent's composition.…”

“…Results form that study acknowledged that the sintering profiles affected both density and hardness through grain growth promotion or retardant [9]. The use of fiber reinforcement was also proven to be effective for the enhancement of mechanical properties of composites [4]. Aluminium-silicon nitride metal matrix composites with 0.5 vol.% Si3N4 fibre powder reinforcement were produced through the powder processing technique and then sintered at 600 ºC for 1 hour.…”