In this article, an attempt has been made to the development of magnesium (AM50)-based hybrid composites with graphite nanofiber (GNFs)/alumina short fiber (Al₂O_3sf) hybrid preforms by infiltration method. The main objective of the present work is to investigate the effect of higher volume percentage of GNFs with the mechanical properties of the Mg/Al ₂O_3sf composites system. Based on the SEM observations, it has been confirmed that the Al₂O_3sf are good dispersed within the matrix metal. However, the GNFs were formed agglomerated within the matrix metal due to the higher volume percentage of GNFs while preforming. The mechanical properties such as hardness, tensile strength, and compressive strength of composites improved upto a threshold of 10% volume fraction of fibers. When the volume fraction of fibers was above 10% the properties showed to decreasing trend due to the presence of GNFs agglomerations. In the present hybrid composites, even though GNFs existed as clusters their distribution within the array of Al₂O_3sf network are found to be relatively good. It suggests that a critical amount of GNFs agglomerates may actually be beneficial for the mechanical properties of the composites.

Nano-microhybrid reinforced metal matrix composites are the novel combination of composite system which enhanced the mechanical properties of the metal matrix composites. The aim of this study is to determine the nano- and macromechanical properties of aluminium (A356)-based hybrid composites reinforced with multiwall carbon nanotubes and alumina short fibers (Al₂O₃sf). Hybrid preforms were developed initially, by a combination of multiwall carbon nanotubes and Al₂O₃sf with total volume fractions of 10%, 15% and 20% and by varying the weight percentage of multiwall carbon nanotubes such as 1%, 2% and 3%. The fabricated hybrid preforms were then infiltrated with aluminium alloy (A356), and the microstructure and mechanical properties of the composites were evaluated. The distribution of multiwall carbon nanotubes within the array of the Al₂O₃sf network which exists in clusters was found to be relatively good. The mechanical properties such as the hardness and tensile strength of Al-based hybrid metal matrix composites were found to be improved by up to 2 wt% of multiwall carbon nanotubes. The causative reason for this is attributed to a combined effect of both multiwall carbon nanotubes and Al₂O₃sf, which contributed to better load sharing between the fibers and the Al matrix, and also accounted for the resistance of dislocation movements caused by the presence of the multiwall carbon nanotubes. In addition, the continuous stiffness measurement method was also used to evaluate the nanomechanical properties of the composites. The results showed that the influence of multiwall carbon nanotubes highlighted the properties on a nanoscale.

Finite element (FE) analysis of the tensile test of TWB-HPF 22MnB5 steel was performed and compared with the experimental results. To improve the accuracy of the simulation, the damage theory of FLD and ductile damage theory were used in 2D and 3D simulations. The tensile strength of 22MnB5 steel was determined under various welding heat inputs for FE simulation. Crack propagation of the welded region indicated that the fracture was observed in the base metal under normal welding conditions. Also, the crack propagated along the HAZ region due to higher heat input of the welding, and lead fractures have been highlighted as a potential complication.

The present article describes the tribological properties of Mg-based hybrid composites reinforced with graphite nanofiber (GNF) and alumina short fiber (Al₂O_3sf) that were investigated. The Mg/GNF/Al₂O_3sf hybrid composites with varying volume fraction of fiber (10 vol.%, 15 vol.%, 20 vol.%) were developed. SEM observations indicate that the GNF cluster distributions within the array of the Al₂O_3sf network are found to be relatively good. The Taguchi design of the experiment has been applied to conduct the wear test, and the statistical analysis of variance (ANOVA) has been used to evaluate the influence of wear test parameters on the wear loss and coefficient of friction (COF) of the composites. The influence of wear test parameters such as volume fraction of fiber (VF), applied load (AL), sliding distance (SD), and sliding speed (SP) on the wear loss and COF of composites was analyzed under dry sliding conditions. The results of ANOVA indicate that the sliding distance was found to be the prominent factor affecting wear loss, and the applied load influenced the COF most significantly. Furthermore, the composites with 20 vol.% of fiber had lower wear loss than those with 10 vol.% and 15 vol.% of fiber. The COF of composites with 15 vol.% of fiber was found to be slightly lower compared to the 10 vol.% and 20 vol.% of fiber cases. The results imply that the hybridization of GNFs and Al₂O_3sf, as well as the formation of Mg₁₇Al₁₂ and Al₂MgC₂ precipitates enhanced the tribological properties of the Mg hybrid composites.