Influence of aluminium content on the microstructure and densification of spark plasma sintered nickel aluminium bronze

Avwerosuoghene Moses Okoro,Senzeni Sipho Lephuthing,Peter Apata Olubambi,Samuel Ranti Oke

doi:10.1051/mfreview/2021006

Avwerosuoghene Moses Okoro, Senzeni Sipho Lephuthing + Show 2 more

Open Access

https://doi.org/10.1051/mfreview/2021006

Copy DOI

Journal: Manufacturing review	Publication Date: Jan 1, 2021
Citations: 1	License type: CC BY 4.0

Affiliation: University of Johannesburg

Abstract

In this study, nickel aluminium bronze alloys (NAB) with appreciable densification and improved microhardness was consolidated via spark plasma sintering technique. The NAB alloy was synthesized from starting elemental powders comprised nickel (4 wt.%), aluminium (6, 8 & 10 wt.%) and copper using dry milling technique. Starting powders were homogeneously milled using gentle ball mill for 8 h at a speed of 150 rpm and a BPR of 10:1. Subsequently, the milled powders were consolidated using the spark plasma sintering technique at 750 °C under a compressive pressure of 50 MPa and rate of heating (100 °C/min). Furthermore, the powders and sintered alloys were characterized using SEM and XRD to ascertain the microstructural and phase evolutions during the synthesis of the NAB. The density and microhardness of the alloys were further investigated to ascertain the integrity of the sintered alloys. The results indicated that the increase in aluminium content resulted in the formation of intermetallic and beta phases on the alloy after sintering and the microhardness of the alloys improved with the increase in aluminium content.

Highlights

Nickel aluminium bronze alloys (NAB) are extensively desirable for oil and gas as well as marine applications especially for the production of pumps, impellers, pipes owing to its outstanding strength and degradation resistance in turbulence corrosive environments [1,2]
The powder metallurgy (PM) route has advantages over conventional casting techniques for producing materials with uniform microstructures and less segregated grains, which result in improved material properties
In a bid to synthesis NAB alloy with improved densification and microhardness, the Spark plasma sintering (SPS) technique was employed in this study to fabricate NAB with varying concentration of aluminium and the influence of aluminium content on the density and microhardness was investigated

Summary

Introduction

Nickel aluminium bronze alloys (NAB) are extensively desirable for oil and gas as well as marine applications especially for the production of pumps, impellers, pipes owing to its outstanding strength and degradation resistance in turbulence corrosive environments [1,2]. The NAB alloys have complex composition and microstructures that requires appropriate manufacturing technique and heat treatment to unveil its unique properties [3]. This alloy usually contains aluminium (6–13 wt.%), nickel (Ni) up to 7 wt.% and copper (Cu). The PM route has advantages over conventional casting techniques for producing materials with uniform microstructures and less segregated grains, which result in improved material properties. Material systems namely composites, alloys, ceramics and polymers [12] This technique uses pulse direct current alongside compressive pressure to rapidly consolidate materials without allowing significant grain growth. In a bid to synthesis NAB alloy with improved densification and microhardness, the SPS technique was employed in this study to fabricate NAB with varying concentration of aluminium and the influence of aluminium content on the density and microhardness was investigated

Materials and method

Microstructural analysis of the powders and fabricated NAB alloys

Phase analysis of the powders and the fabricated NAB samples

Density and microhardness of the fabricated NAB samples

Conclusion