A Detailed Study on using Novel LM 25 Aluminium Alloy Hybrid Metal
Matrix Nanocomposite for Nuclear Applications
Authors: Naidu S.C.V. Ramana Murty , Vellingiri Suresh , Prabhu Paulraj , Hussain Beporam Iftekhar , Asary Abdul Rab , Padmanaban Govindarajulu , Srinivasnaik Mukuloth , Yuvaraj Kunnathur Periyasamy 
Published: March 2024

Aim::

This article describes the use of graphite(Gr) and boron carbide (B4C) as multiple nanoparticle reinforcements
in LM25 aluminum alloy. Because boron carbide naturally absorbs neutron radiation, aluminium alloy
reinforced with boron carbide metal matrix composite has gained interest in nuclear shielding applications. The primary
goal of the endeavor is to create composite materials with high wear resistance, high microhardness, and high ultimate
tensile strength for use in nuclear applications. Patents on Gr and B4C can cover a wide range of subjects, including
the synthesis and production methods of structural, armor materials, abrasives, and nuclear shielding.

Background::

Science and Technology have brought a vast change to human life. The human burden has been minimized
by the use of innovation in developing new and innovative technologies. To improve the quality of human life,
fresh, lightweight, and creative materials are being used, which play a vital role in science and technology and reduce
the human workload. Composite materials made of metal are being used because they are lightweight. Neutron absorption,
high ultimate strength, high wear resistance, high microhardness, high thermal and electrical conductivity, high
vacuum environmental resistance, and low coefficient of thermal expansion under static and dynamic conditions are all
demands for the hybrid metal matrix composites utilized in nuclear applications.

Objective::

Stir casting is used to create the novel LM 25 aluminum alloy/graphite and boron carbide hybrid nanocomposites.
• The mechanical properties such as ultimate tensile strength, yield strength, percentage of elongation, microhardness,
and wear behavior are calculated.
• Three analyses are performed: microstructure, worn surface analysis, and fracture analysis of the tensile specimen.

Method::

• Stir casting process
• Tensile, Hardness, Wear Test
• Materials Characterization – FESEM, Optical Microscopy, EDS

Results::

The mechanical properties values are 308.76 MPa, 293.51 MPa, 7.8, 169.2 VHN, and 0.01854mm3/m intended
for ultimate tensile strength, yield strength, percentage of elongation, microhardness, and wear behavior, respectively.
This implies that the synthesized composite may be used in nuclear applications successfully

Conclusion::

The subsequent explanation was drawn from this investigative work:
• The LM 25/B4C/Gr hybrid nanocomposite was successfully manufactured by employing the stir casting technique.
For nuclear shielding applications, these composites were prepared with three different weight percentages
of nanoparticle reinforcements in 2,4,6% Boron carbide and constant 4 wt.% graphite.
• The microhardness values of the three-hybrid nanocomposite fabricated castings were determined to be
143.4VHN, 156.7VHN, and 169.2VHN, respectively.
• The hybrid nano composite's microstructure revealed that the underlying LM 25 aluminum alloy matrix's finegrained,
evenly dispersed nanoparticles of graphite and boron carbide were present.
• The microtensile test was carried out and it was found that the ultimate tensile strength, yield strength and percentage
of elongation values are 281.35MPa, 296.52MPa, 308.76MPa, 269.43, 274.69, 293.51 and 3.4, 5.7, 7.8
respectively.
• Deformation caused the hybrid LM 25/B4C/Gr nanocomposite to fracture in ductile mode. Dimples and cavities
are seen in the fracture because of the nanoparticle reinforcements and the matrix's tight connection.
• The wear loss of nanocomposite based on the input parameter applied load, sliding velocity and sliding distance values
are 0.02456, 0.02189, 0.01854, 0.02892, 0.02586, 0.02315 and 0.02682, 0.02254, 0.02015 mm3/m, respectively.
• The LM 25 alloy's elemental analysis displays the aluminum alloy phase as the largest peak and the remaining
elements as smaller peaks; also, the spectral analysis reveals the presence of boron (B), graphite (C), silicon, and
ferrous in the aluminum alloy LM 25.
• Through worn surface FESEM investigation, it was shown that under sliding and high load situations, debris, delamination,
and groove develop. Further rupture, fine, and continuous grooves were seen when low stress and
sliding circumstances were applied to the LM 25/B4C/Gr and stir cast specimen. This result implies the presence
of mild adhesive and delamination wear processes.