Influence of hybrid pin profile on microstructural and mechanical properties of Al/SiC graded composites produced by friction stir processing

Friction stir processing (FSP) was employed to fabricate a surface graded composite by embedding SiC reinforcement particles in an AA6082-T6 matrix. Conical blind holes were drilled on the surface of the plate with varying inter-hole distances. The processing was performed with the different number of passes by keeping rotational and traverse speed constant. A new hybrid tool with a combination of conventional conical threaded tool and the triangular cross-sectioned tool was used in processing. The microstructural features of the processed samples were examined by a 3D microscope and scanning electron microscope (SEM). Mechanical properties such as microhardness, tensile strength was thoroughly evaluated. It is reported that the number of passes played an essential role in the distribution of reinforcement particles and grain refinement. The hardness value improved by applying multiple passes. The fractured tensile samples showed ductile failure. The sample treated with double passes gave better results with the homogenous distribution of reinforcement particles compared to samples processed with a single pass.

A Study On Effect of SiC And OFHC Cu-Fe29Ni17Co Reinforcement With AA7075 On Microstructure, Mechanical And Wear Rate of Hybrid Composites

The silicon carbide (SiC) reinforcement with aluminium alloy 7xxx series has been found to be limited value as per the mechanical properties and wear behaviour of previous studies. In order to improve limited mechanical properties of hybrid aluminium metal matrix composites, the SiC and OFHC Cu-Fe29Ni17Co reinforcement has been added with AA7075 alloy. Hence, the AA7075/SiC/Cu-Fe-Ni hybrid composites have been fabricated through a stir casting route under different weight percentages of SiC reinforcement. The mechanical properties such as hardness, compressive strength, tensile strength and wear rate have been investigated. The micro structure of hybrid composites found that the reinforcement particles in matrix alloy have been evenly spread. The silicon carbide and Cu-Fe-Ni alloy in aluminium solid solution has been found as well bonded interfacial reactions. The hardness, tensile strength, yield strength, compressive strength and wear rate were improved by 23.9 %, 48 %, 47 %, 15.3 % and 70 % for hybrid composite by adding 15 wt. %SiC and 15 wt. % Cu-Fe-Ni with AA7075 alloy, compared to matrix alloy.

Improvement of mechanical properties of HfB2-based composites by incorporating in situ SiC reinforcement through pressureless sintering

HfB2, Si, and activated carbon powders were selected to fabricate 0–30 vol% SiC reinforced HfB2-based composite. Pressureless sintering process was performed at 2050 °C for 4 h under a vacuum atmosphere. Microstructural studies revealed that in situ SiC reinforcement was formed and distributed in the composite according to the following reaction: Si + C = SiC. A maximum relative density of 98% was measured for the 20 vol% SiC containing HfB2 composite. Mechanical investigations showed that the hardness and the fracture toughness of these composites were increased and reached up to 21.2 GPa for HfB2-30 vol% SiC and 4.9 MPa.m1/2 for HfB2-20 vol% SiC, respectively. Results showed that alpha-SiC reinforcements were created jagged, irregular, and elongated in shape which were in situ formed between HfB2 grains and filled the porosities. Formation of alpha-SiC contributed to improving the relative density and mechanical properties of the composite samples. By increasing SiC content, an enhanced trend of thermal conductivity was observed as well as a reduced trend for electrical conductivity.

Effect of 6 wt.% Particle (B4C+SiC) Reinforcement on Mechanical Properties of AA6061 Aluminum Hybrid MMC

Aluminum based hybrid metal matrix composite with more than two particle reinforcement is very much popular for heavy duty application. In the present study, mechanical properties of AA6061 based hybrid composite synthesized using liquid metallurgy route with 6 wt. % total reinforcement (B 4 C+SiC) with different proportions of B 4 C wt. % and SiC wt. % were investigated. Hardness measurement and uniaxial loading techniques were used to characterize the mechanical properties of the as-cast hybrid composites. The improvement in mechanical properties, such as Vickers hardness value, UTS, yield strength and elongation were tried to explain using various hypothesis proposed by previous studies. The role of clustering theory and effect of binary eutectic Mg 2 Si phase have played a key role in defining the mechanical properties of the hybrid composites. Addition of Alkaline Earth Metal (Mg) during the synthesis process have led to the exploration of some interesting results from the uniaxial tensile loading tests.