Copyright © 2018 Mxolisi B. Shongwe et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. International Journal of Engineering & Technology, 7 (3) (2018) 1581-1584 International Journal of Engineering & Technology Website: www.sciencepubco.com/index.php/IJET doi: 10.14419/ijet.v7i3.9618 Research paper The effects of particle size distribution and sintering conditions on bending strength of sintered Ni-30%Fe alloys Mxolisi B. Shongwe 1 , Olawale O. Ajibola 2 *, Munyadziwa M. Ramakokovhu 1 , Peter A. Olubambi 2 1 Institute for Nano-Engineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria, South Africa 2 Centre of NanoEngineering and Tribocorrosion, University of Johannesburg, Johannesburg, South Africa *Corresponding author E-mail: olawalea@uj.ac.za Abstract This work reports effect of the powder grain size distributions on the bending strength sintered Ni-30%Fe alloys obtained from mixed coarse-fine micron size metal powders. Two dissimilar particle sizes of Ni and Fe metal powders were mixed by subjecting them to translational and rotational agitations using the T2F Turbula Shaker Mixer. The mixed powders were moulded using graphite dies and sintered in vacuum and at constant pressure using Spark Plasma Sintering furnace (HHPD-25). The ratios of the two metals were varied as well as the sintering temperature and time. The morphology and microstructures of both powders and sinters were studied using field emission scanning electron microscopy (JSM-7600F) equipped with energy dispersive X-ray spectrometer (EDS) facilities. The phases in the sintered specimens were characterized by X-ray diffraction (XRD). The densities of the samples were determined, The Vickers mi- crohardness at room temperature and bending strength of the sintered alloy specimens were measured. Comparatively, low heating rate (50 o C/min) produced enhanced microstructures hence higher bonding, bending strength and densification than samples at high heating rate (150 o C/min). Keywords: Sintering; Grains; Bending Strength; Particle Size. 1. Introduction The use of advanced materials in different areas of modern tech- nology has lead to enhancement in the function, quality and per- formance of engineering parts and systems [1]. Nickel-base alloys are unique with combinations of properties making them useful in diverse dedicated applications. The soft magnetic properties of Ni- Fe alloys are used in electronic, electromagnets and communica- tion equipments. Ni-Fe alloys have low expansion characteristics due to balance between thermal expansion and magnetic property changes with temperature. Also Ni-Fe alloys are useful in storage and transportation tanks for liquid natural gas industry; transduc- ers (45-50Ni-Fe), magnetic amplifiers (oriented 49Ni-Fe), sensi- tive direct current relays (45-49Ni-Fe, 78.5Ni-Fe), temperature compensator (29-36 Ni-Fe), shielding (49Ni-Fe), dry reed magnet- ic switches DRMS (51Ni-Fe), chart recorder (instrument) and synchronous motors (49Ni-Fe). Some other properties of significance that enlarge the usefulness of Ni alloys include: the shape memory characteristics of nickel alloys, the high strength at elevated temperatures, and the re- sistance to stress relaxation. Soft magnetic Ni-Fe alloys consisting about 30 to 80% Ni are used extensively for their high saturation magnetostriction and constant permeability with changing temper- ature. For high expectation of ductility and malleability, Ni-Fe alloys are usually made as strip or sheet product; though, billet, bar, and wire can be produced as required [2] Production of cast Ni-Fe from melt can be difficult due to the chemical reactivity of the melt that frequently results in segrega- tion defects [3]. Powder metallurgy (PM) methods to formulate Ni-SMA were affected by the complications faced with usual methods. PM is a practice that lessens the problems related to liquid metal casting, permits a precise composition management and the capability to manufacture a range of components shapes. Therefore, conventional sintering is seen as a viable method of making porous Ni SMA [4]. However, dense materials are not easy to attain, mostly when starting with elemental powder [5]. Sintering process can be realized in the two-stage regime; involv- ing the preliminary sintering of P/M compacts in solid phase and the final sintering with liquid phase executed in vacuum [6]. Sinter-hardening technique SHT presents another way of harden- ing metal powder components beside the traditional austenitiza- tion, quenching, and tempering routines. SHT has numerous ad- vantages such as the reduced number of manufacturing procedures and averting part contamination with oil. SHT can be accom- plished in different ways as using sintering furnaces with custom- ized ferrous PM alloy admixture systems and using dedicated PM alloys in combination with furnaces having fast cooling zones. SHT compact the PM component, sinter, and temper in a cycle with optimization of each step to guarantee consistent making of sinter-hardened parts [7]. Though, there are reports on the binary alloys of Nickel with iron group elements. The gap still exists in relating and understanding the roles of diversities in powder metal grain sizes as regarding the densification and sintering parameters on the enhancing superior mechanical (bending strength) and magnetic characteristics (mi- crostructure) of Ni-Fe alloy in particular [8-11]. There is still great necessity to investigate the Ni-Fe alloy systems more intensely. Hence this work studied the influence of grain particle size distri- bution and sintering parameters (Heating rate (°C/min), reference temperature ( o C) and dwell time (min)) on the bending strength of the sintered Ni-30%Fe alloys produced from the mixture of