Applied Surface Science

(1)

Full Length Article

Structural and magnetic properties of FeCuNi nanostructured produced by mechanical alloying

A. Younes

^a,b,^⇑

, N. Dilmi

^b

, M. Khorchef

^a

, A. Bouamer

^a

, N-E. Bacha

^b

, M. Zergoug

^a

aResearch Center in Industrial Technologies CRTI Cheraga, Algiers, Algeria

bLaboratory of Surface Treatment & Materials, University of Saad Dahleb, Blida, Algeria

a r t i c l e i n f o

Article history:

Received 11 October 2017 Revised 13 December 2017 Accepted 18 December 2017 Available online 24 December 2017

Keywords:

FeCuNi nanostructured Mechanical alloying MEB

DRX VSM

a b s t r a c t

We investigated the magnetic, morphological, and structural properties of FeCuNi. The powder alloy is elaborated by mechanical alloying process for 10 h with varying the Cu content. The aims of this work are to study the effect of Ni/Cu ratio on the magnetic and microstructure properties. The crystallite size decreases with the increase of Ni. The reduction of crystallite size proceeds slowly until 17 nm for 30% of Ni. Coercivity and saturation magnetization increases from 105.4 Oe, 122.568 emu/g to 156.77 Oe, 140.679 emu/g respectively caused by the increase of the concentration of Cu and dislocation density as well as the decrease of the crystallite size.

1. Introduction

Nanocrystalline metallic materials can be produced by the methods of powder metallurgy [1,2]. Fe is an excellent ferromag- netic material. Ni is a hard metal with magnetic properties similar to Fe. The substitution of Fe by one of transition metal elements affects the lattice parameter as good as the magnetic, electromag- netic and mechanical properties [3,4].

A preliminary study for the Combination of Fe-Ni-Cu alloys as a good compromise, the copper have a good sinterability when asso- ciated with nickel, and it improves the hardness of the iron-based alloy. The sinterability of the powder should be further improved by the use of a fine powder from an innovative process. This combination of alloys is totally new [5–10].

The presence of Ni is beneficial to the nucleation of Cu precipi- tates and has little effect on coarsening rate, which indicates that Ni atoms accelerate Cu diffusion in ferric alloy. The Cu atoms and Ni atoms interact with each other during the formation of Cu pre- cipitates in Fe matrix. So we divide the Cu diffusion into three stages according to different interaction behaviors between Cu and Ni atoms. Stage I is for the free diffusions of Cu and Ni atoms and Ni atoms can promote Cu precipitation obviously, stage II is for the mutual promotion between Ni and Cu atoms, and stage III is for

the inhibition of Ni atoms on Cu diffusion. Cu and Ni atoms gather into small clusters, and then these small clusters grow into big ones, acting as precipitation precursors [11–14].

The aims of our work are following the powder metallurgy process to develop a new alloy by studying the phase equilibrium in the ternary system Fe-Ni-Cu and composition around the industrial process, characterization of microstructures and phase trans- formations are studied by X-ray diffraction and magnetic properties are determined by Vibrating samples manometers (VSM).

2. Materials and experimental procedures

The preliminary elemental powders of particle size are 80, 55

l

^{m and 60}

l

m and 99.5%, 99.9% and 99.9% of purity for Fe, Ni and Cu respectively. The elemental Fe, Ni and Cu powders are milled in a high energy planetary ball mill PM400 under argon atmosphere using hard chromium balls. The compositions of the initial powder mixtures were Fe70Cu30-xNix. (x = 0, 10, 15, 20 and 30). The weight ratio of powder to balls was around 1:20.

The milling time was 10 h. The ball milling process has two purposes: to make FeCuNi alloys and to reduce the grain sizes via severe plastic deformation. The powders produced after milling were investigated by using Gemini SEM 300 attached with EDX unit (Energy Dispersive X-ray Analyses), with acceler- ating voltage 30 kV. Morphology, size and particle distribution were examined of the milled powders were quantified by visual

⇑Corresponding author at: Research Center in Industrial Technologies CRTI, P.O.

Box 64, Cheraga 16014, Algiers, Algeria.

E-mail address:[email protected](A. Younes).

Applied Surface Science 446 (2018) 258–265

Contents lists available atScienceDirect

Applied Surface Science

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / a p s u s c