Effect of deformation temperature and degree on tensile properties of the extruded 2024Al/Al18B4O33w composite with extrusion – forging multistage hot deformation

The effect of extrusion – forging multistage hot deformation on tensile properties of the 2024Al/Al₁₈B₄O₃₃w composites is investigated. The extruded 2024Al/Al₁₈B₄O₃₃w composites are used as blanks. The tensile properties of the extruded 2024Al/Al₁₈B₄O₃₃w composite followed by secondary deformation are studied. The effects of holding temperature and deformation degree on tensile properties of the extruded composite are discussed. The results show that due to the reduction in stress concentration and dislocations, ultimate tensile strength of the extruded 2024Al/Al₁₈B₄O₃₃w composite held at 400 °C for 1 h is lower than that of the extruded composite without holding. Increasing holding temperature from 300 °C to 450 °C, ultimate tensile strength of the extruded 2024Al/Al₁₈B₄O₃₃w composite increases firstly and then decreases. The extruded 2024Al/Al₁₈B₄O₃₃w composite held at 400 °C for 1 h followed by secondary forging with the larger length to width ratio of 4 : 1 has the ultimate tensile strength of 456.1 MPa, higher than that of the extruded 2024Al/Al₁₈B₄O₃₃w composite without secondary forging.     

Process optimization and microstructural analysis of aluminum based composite reinforced by multi‐walled carbon nanotubes with various aspect ratios

The dispersion of carbon nanostructures in metallic matrix with strong bonding is a very important challenge to achieve a composite with high mechanical properties. In this work, the effect of aspect ratio of reinforcement phase, weight percent and using improved mechanical alloying process and sonication on the well dispersion of multiwalled carbon nanostructures (MWCNTs) were investigated. Moreover, the hot pressing conditions were optimized by factorial design technique to achieve the highest relative density. Field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM) and X‐ray diffraction were used to analyse the microstructure. Also, the particle size of the grain structure of composite containing multi‐walled carbon nanotubes determined for evaluating the influence of aspect ratio on grain growth. The results verified that by using conventional method of alloying, grinding process and agglomeration of 2 wt% multi‐walled carbon nanotubes with long length can be occurred. By decreasing the weight percent of multi‐walled carbon nanotubes to 1 wt%, dispersion process progressed slightly. Short length multi‐walled carbon nanotubes showed more clustering and minor damage in both 1 and 2 wt%. By using modified design of alloying (using magnet), both types of multi‐walled carbon nanotubes dispersed better than conventional design in the matrix with good bonding at initial times.     

A preliminary study on the manufacturing aluminum–potassium feldspar metal matrix composite materials

This study reports the results of a preliminary study of manufacturing aluminum–potassium feldspar metal matrix composites including its castability and mechanical properties. The material was composed considering 0.25 %, 0.5 %, and 0.75 % additive ratios to examine the impact of the amount of potassium feldspar on the material and mechanical properties of the manufactured aluminum metal matrix composite material. Aluminum alloy (A356) was utilized as the matrix of the composition. The composite material was manufactured by the stir casting technique. The modulus of elasticity, yield strength, tensile strength, elongation, density, and quality index of the material parameters was taken into account to determine the materials′ practicality. The preliminary results indicated that potassium feldspar is a promising mineral to be utilized as an additive for aluminum metal matrix composites since it has a positive impact on mechanical properties. By optimizing the casting parameters, the positive aspects of the potassium feldspar may make the material more practical to be utilized in vast engineering applications.     

Machinability and surface morphology investigations of multiwall carbon nanotube reinforced aluminium 7075 metal matrix composite during electrical discharge machining: A grey relational approach

Multiwall carbon nanotube buttressed aluminium 7075 metal matrix composite was synthesized through an amended liquid metallurgy method, which consisted semisolid stirring, ultrasonic treatment and squeeze casting. Aim was to investigate its machinability and surface morphology during electrical discharge machining. Variable machining factors were peak current, pulse-on time and gap voltage, whereas the responses under investigation were electrode wear rate, material removal rate and average surface roughness. Results revealed electrode wear rate, material wear rate and average surface roughness increased on increasing peak current and pulse-on time, but all these responses behaved inversely with the increase of gap voltage. Average surface roughness reduced by around 44 % on reducing the peak current from 10 A to 4 A and increasing gap voltage from 55 V to 80 V at constant pulse-on time of 300 μs; however, it increased by around 25 % on reducing the gap voltage from 80 V to 55 V and increasing the pulse-on time from 100 μs to 300 μs at constant peak current of 10 A. Significance of the process parameters were verified, regression models were developed and morphology of the machined surfaces was studied. Finally, multiple response optimization was conducted following grey relational approach.