Abstracts Book - IMRC 2018

• SA2-O027
SYNTHESIS AND CHARACTERIZATION OF NANOCRYSTALLINE
NiAlCu BY MECHANICAL ALLOYING.
Manuel Eduardo Serrano Nava 1 , Arturo Molina Ocampo 1 , Rene Guardian 1
1 Universidad Autónoma del Estado de Morelos, Centro de Investigación en Ingeniería y
Ciencias Aplicadas, Mexico.
The nanocrystalline Ni50Al45Cu5 compound was synthetized by mechanical
alloying of elemental powders. The defect structure of β NiAl with copper
substituted for aluminum in 5 a.t.% fixed concentration ratio is studied. The
mechanical alloying resulted in the gradual formation of nanocrystalline
Ni50Al45Cu5 compound with a grain size of 14 nm. It was found that Ni50Al45Cu5 is
composed of the phase β-Al(Ni,Cu). The Ni50Al45Cu5 compound exhibited high
microhardness value of 320 Hv. The XRD patterns of Ni50Al45Cu5 powder mixture
as received powder showed diffraction peaks of the pure crystalline Ni, Al and
Cu. In the early stage of milling, only the broadening of the Ni, Al and Cu peaks
and remarkable decrease in their intensities occurred as result of the
refinement of the crystallite size and enhancement of the lattice strain.
Increasing milling time to 10 h led to the disappearance of the Ni, Al and Cu
peaks while Ni50Al45Cu5 peaks began to appear. Complete transformation of
elemental Ni, Al and Cu powder mixture to the β NiAl intermetallic phase + β-Al
(Ni, Cu) phase occurred after 20 h of ball milling time. The Ni50Al45Cu5 phase after 10
h and 20 h milling times had a crystallite size of 16 nm and 14 nm and a lattice
strain of 0.35 and 0.40 respectively. While the Ni50Al45Cu5 phase crystallite size
remain unchanged upon further milling, its lattice strain increased with
increased time milling time to 20 h. The long range order of the compound is
also affected by the milling time. Then we can asumme that the increase in the
Hardeness of the compoun is related to the defects , deformation and
refinement of the crystalline structure. The suggestion that the point defects
order to form the Ni2AI3 phase for Al-rich NiAI or Ni2A1 for Ni-rich NiAI, leaving
the bulk of the material in a higher degree of order, is not consistent with X-ray
scattering studies. The long range ordering decrease is consistent with precision
X-ray diffraction measurements, although short range order may exist.
Acknowledgment:
CONACYT