Microstructure and Mechanical Properties of AZ91 Rein-Forced with High Volume Fraction of Oriented Short Carbon Fibers

Abstract

In this study, AZ91/23 vol.% short carbon fiber composite was produced by a squeeze casting technique using a cylindrical pre-form of treated carbon fibers, in which the fibers are randomly oriented in the horizontal plane. Cylindrical specimens (height = 9 mm and diameter = 6 mm) were machined from the as-cast AZ91 matrix and its composite. The full behavior of the produced composite was studied through the test specimens machined in two directions, namely parallel to the reinforced plane (in the radial direction of the cast cylinder) and normal to the reinforced plane (in the axial direction of the cast composite). The microstructures of the produced composite specimens were investigated using SEM equipped with EDS analysis. Density, hardness, compressive, and wear behavior were also investigated. For comparison, the AZ91 matrix was evaluated as a reference. The microstructure of the produced AZ91 matrix alloy and its composite revealed dense materials without casting defects. Both composite specimens show improvement in hardness, compressive strength, and wear properties over the AZ91 matrix. The compressive and wear properties are more fiber orientation-dependent than the hardness results. The parallel composite specimen depicts the highest compressive properties in terms of yield compressive strength (311 MPa) and ultimate compressive strength (419 MPa), compared to that shown by the AZ91 matrix and the normal composite specimen. This improvement in compressive strength was at the expense of ductility. The parallel composite specimen shows the lowest ductility (R = 3.8%), compared to that given by the normal composite specimen (R = 7.1) and the AZ91 matrix alloy (R = 13.6). The wear testing results showed that at the highest wear load of 5 N, the material weight loss of the parallel composite specimen decreases by 44% and 64% compared to the AZ91 matrix and the normal composite specimen, respectively.

Tensile Deformation and Fracture of Unreinforced AZ91 and Reinforced AZ91-C at Temperatures up to 300 °C

“…This arrangement makes the loading of the test specimens parallel to the reinforced plane to have a strengthening effect. Previous studies on AZ91-C [ 14 , 30 ] indicated that the achieved compressive strength [ 30 ] and wear resistance [ 14 ] were lower for samples loaded normal to the reinforced plane (parallel to the cylindrical cast part axis) than that for specimens loaded parallel to the reinforced plane.…”

“…The squeeze cast composite was solidified at a rapid cooling rate, reaching around 28.2 °C s −1 . More detailed information about this squeeze casting production technique can be found in the following descriptions [ 14 , 30 , 32 ].…”

“…Obviously, this is an attraction to research it further. In the present study, the AZ91 alloy was reinforced with short carbon as it is established from previous results that the addition of short carbon fibers is very effective in increasing the strength, wear resistance, and hardness of the AZ91 alloy [ 14 , 30 ]. Therefore, the main objectives of this work are: (1) to present lightweight and high- reinforcement volume fraction (23%) composite material with improved tensile properties, (2) to model the tensile deformation and flow behavior of the cast Mg-alloy AZ91 and present the description parameters for researchers for FE simulation tasks, and (3) to present the role of carbon short fibers and their orientation on the fracture behavior of the AZ91-C composites.…”

Surface Modification of Brass via Ultrashort Pulsed Direct Laser Interference Patterning and Its Effect on Bacteria-Substrate Interaction

“…Here, few points with lower oxygen at.-% have a Cu-Zn ratio that corresponds to the stoichiometry of the β phase of brass. 56,57 After etching, the uppermost layer still has increased amounts of zinc and oxygen (see Figure 2c and Table 1). However, the chemical modification is only observed for ∼100 nm from the surface.…”

LCF and HCF of Short Carbon Fibers Reinforced AE42 Mg Alloy

“…Not only that, there are other methods that are also usually undertaken to enhance the mechanical properties of magnesium alloys, namely by adding reinforcing materials to magnesium alloys to make magnesium alloy-based composites in order to upgrade their mechanical properties as required. Referring to several studies that have been conducted previously, incorporating reinforcement materials into magnesium alloys in the form of SiO 2 nanoparticles [ 13 ], carbon nanotubes/CNTs [ 14 ], and short fibers of Al 2 O 3 [ 15 ] or carbon [ 16 ] can considerably improve their mechanical strength [ 15 , 17 ] and creep resistance [ 18 ]. Indeed, short carbon fiber reinforcement has the advantages of increasing stiffness, elastic modulus, and creep resistance while maintaining a light weight, opening up opportunities to expand its use in different engineering applications [ 19 ].…”