In this study, to fabricate neutron shielding material, boron carbide (B₄C)-reinforced aluminum (Al) alloy composites were successfully fabricated by stir casting followed by a hot rolling process. Microstructural analysis of B₄C/Al6061 composites with different volume fractions (5, 10, 20, 25, and 30%) revealed that the composites had volume ratios similar to the target volume ratios of B₄C. Furthermore, B₄C reinforcements were uniformly dispersed in the Al matrix, forming multi-interfacial layers of Al₄C₃/(Ti,Cr)B₂. The interfacial layer generated during stir casting maintained its own structure after the hot rolling process, indicating strong interfacial bonding strength. The tensile strengths of the B₄C/Al6061 composites increased to 20 vol.% and stayed above the value for Al6061, even reaching 30 vol.%. The measured thermal neutron shielding rate increased with increasing B₄C content, and the highest thermal neutron shielding rate was observed at 30 vol.% composite, which corresponds to 95.6% neutron shielding at 0.158-cm thickness.

In this study, to evaluate the effect of boron carbide (B₄C) addition on the wear performance of aluminum (Al), Al6061 and 5, 10, and 20 vol.% B₄C/Al6061 composites were manufactured using the stir casting and hot rolling processes. B₄C particles were randomly dispersed during the stir casting process; then, B₄C particles were arranged in the rolling direction using a hot rolling process to further improve the B₄C dispersion and wear resistance of the composites. Furthermore, a continuous interfacial layer between B₄C and the Al6061 matrix was generated by diffusion of titanium (Ti) and chromium (Cr) atoms contained in the Al6061 alloy. Wear depth and width of the composites decreased with increasing B₄C content. Furthermore, with B₄C addition, coefficient of friction (COF) improved as compared with that of Al6061. The results indicate that interface-controlled, well-aligned B₄C particles in the friction direction can effectively increase the wear properties of Al alloys and improve their hardness.

This study was conducted on titanium diboride (TiB₂) reinforced Al metal matrix composites (MMCs) with improved properties using a TiB₂ and aluminum (Al) 1050 alloy. Al composites reinforced with fine TiB₂ at volume ratios of more than 60% were successfully fabricated via the liquid pressing infiltration (LPI) process, which can be used to apply gas pressure at a high temperature. The microstructure of the TiB₂–Al composite fabricated at 1000 °C with pressurization of 10 bar for 1 h showed that molten Al effectively infiltrated into the high volume-fraction TiB₂ preform due to the improved wettability and external gas pressurization. In addition, the interface of TiB₂ and Al not only had no cracks or pores but also had no brittle intermetallic compounds. In conclusion, TiB₂–Al composite, which has a sound microstructure without defects, has improved mechanical properties, such as hardness and strength, due to effective load transfer from the Al matrix to the fine TiB₂ reinforcement.

Metal matrix composites (MMCs) produced through the unique liquid pressing infiltration (LPI) process exhibit significant industrial potential. In this study, TiC/FC250 metal matrix composites were fabricated using the liquid pressing infiltration process, and the effects of austempering and quenching–tempering heat treatments on the microstructure and wear characteristics were investigated in comparison to as-cast specimens of both the FC250 gray cast iron matrix material and the TiC/FC250 metal matrix composites without heat treatment. The results indicated that the quenching–tempering heat treatment effectively enhanced the dry sliding friction and wear characteristics compared to the as-cast condition. The heat-treated specimens, under optimal conditions, demonstrated superior properties compared to other heat treatments and the matrix material. Although the metal matrix composites were successfully produced via the liquid pressing infiltration process and optimal heat treatment, some graphite morphology transformed from a flake to a spherical shape due to the high temperature and slow cooling rate during the process. With the quenching–tempering heat treatment, the wear resistance increased by approximately 41.53% in the matrix material and by 53.38% in the metal matrix composites compared to the as-cast specimens. The TiC/FC250 metal matrix composite heat-treated under optimal conditions exhibited an approximate 58.28% reduction in the friction coefficient compared to the FC250 gray cast iron.

A metal matrix composite was developed through a unique liquid pressing infiltration process to study the wear mechanism of a TiC reinforced AISI 1020 steel matrix. The microstructure, hardness, and wear behaviors of the TiC/AISI 1020 composite were compared with commercial AISI 52100 bearing steel. Microstructural analysis showed that there were no defects, such as pores or agglomeration of reinforcement particles, and about 60% of the volume of TiC was uniformly dispersed. In the case of the AISI 52100 alloy, the hardness was 62.42 HRC, which was similar to the 62.84 HRC value of the as-cast TiC/AISI 1020 composite. After the quenching heat treatment, the Rockwell hardness of the composite increased to 76.64 HRC, which was attributed to the martensitic transformation of the AISI 1020 matrix. As a result of the pin-on-disc wear test with high contact pressure, the wear width of AISI 52100 was 2937 μm, which was approximately 4.3 times wider than that of the heat-treated metal matrix composite (682 μm). The wear depths of AISI 52100 and the heat-treated composite were 2.6 μm and 0.5 μm, respectively, indicating that TiC/AISI 1020 exhibited excellent wear resistance compared with bearing steel. Improved wear resistance of the TiC/AISI 1020 composite originates from uniformly distributed TiC, with an increase in the hardness due to the heat treatment.