Effect of Barium (Ba) Addition on Dry Turning of a Commercial Al-20Mg2Si-2Cu Metal Matrix Composite

The principle aim of this study was to observe the effect of machining parameters as well as the separate additions of 0.2wt% barium (Ba) on the machinability of Al-20%Mg2Si in situ metal matrix composite. Microstructure alteration, surface roughness and cutting temperature were taken into account as indices to examine the effect of modifier and machinability during dry turning. The results showed that addition of Ba as modifier reagent results in lower cutting temperature and better surface roughness due to the formation of Ba compound and modification of morphology of Mg2Si reinforcement particle

Wettability enhancement of SiCp in cast A356/SiCp composite using semisolid process

The effects of SiCp treatment and magnesium addition on microstructural and mechanical properties of Al356/20 wt% SiCp semisolid composites were investigated. The results showed that cleaning and oxidizing of SiCp and addition of 1 wt% Mg resulted in improving wettability, incorporation, and uniform distribution of SiCp in A356 matrix. Consequently, the ultimate tensile strength (UTS) value increased by 19% and 32% when the SiC was treated and also when Mg was added, respectively, compared to as-received SiCp. In addition, hardness value increased from 69.7 HV in as-received SiCp to 94.8 HV after SiCp treatment and addition of Mg

Influence of solution heat treatment on microstructure and tensile properties of Gd-Treated Al-15% Mg-2 Si in-situ composites

Microstructural alteration and tensile properties of Al-15% Mg2Si composite specimens was examined after addition of gadolinium (Gd) and conducting solution heat treatment. Various percentages of gadolinium (0.5, 1.0, 2.0 and 5.0 wt. % Gd) were added to the composite Al-15% Mg2Si composite. The specimens then solutionized at 500 °C for 4h followed by quenching. The results showed that regular morphology and small size of primary Mg2Si particles is achieved after addition of 1.0 wt.% Gd compared to untreated composite. Due to solutionizing effect, Mg2Si dissolution occurred which led to alter the morphology of primary Mg2Si particles to round shape. Tensile testing results revealed that enhancement in UTS and El% values owns to influence of both Gd addition and solution heat treatment on the Al-15% Mg2Si composite. The fracture surface of untreated composite depicted a cellular fracture, while the fracture surface of Gd treated and heat treated composite showed a ductile surface containing fine dimples, in which alteration of fracture mode is due to the role of Gd and heat treatment on microstructural modification, which results in reduction of potential sites for stress concentration and crack initiation areas

Microstructural characterization, mechanical and tribological properties of ZC71 hybrid composite reinforced with SiC and MWCNT

In the present study, the influences of different SiC addition, MWCNTs and various SiC particle sizes on the structural, mechanical and tribological properties of ZC71 alloys were studied. The results revealed that the proper amount/size of SiC particles with the addition of MWCNTs had a considerable effect on the microstructural alteration, and mechanical and tribological properties of the ZC71 alloy. The Vickers hardness values of the ZC71 alloy improved with the addition of MWCNT and SiC. The UTS (216 MPa) and El.% (6.95 %) were achieved in the ZC71-5%SiC(15µm)-0.5%MWCNT. The cast ZC71 alloy showed brittle fracture with some quasi-cleavage characterizations. However, by adding 5% SiC (15 µm) and 0.5% MWCNT, the fracture mode changed to ductile fracture. The wear results showed that the ZC71-5%SiC-0.5%MWCNT hybrid composite had the highest wear resistance with the lowest friction coefficient and wear rate. Examination on the worn surface of the ZC71-5%SiC-0.5%MWCNT hybrid composite showed mild abrasion as the governing wear mechanism

Role B4C Addition on Microstructure, Mechanical, and Wear Characteristics of Al-20%Mg2Si Hybrid Metal Matrix Composite

In the current study, the effect of different B4C additions (0, 2.5, 5, and 10 wt%) on the microstructural, solidification behavior, mechanical, and tribological properties of Al-20%Mg2Si composite were studied by means of scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Vickers hardness, tensile, and dry sliding wear tests. The cooling curve thermal analysis (CCTA) approach was utilized to monitor the influence of B4C particles on the solidification behavior of Al-20%Mg2Si composite. The results revealed that the addition of B4C particles up to 10 wt% reduced the nucleation temperature (TN) and growth temperature (TG) of the primary Mg2Si phase. Moreover, the proper amount of B4C added to Al-20%Mg2Si composite has a significant effect on the microstructural alteration, mechanical, and tribological properties of the composite. The mean size of primary Mg2Si in Al-Mg2Si composite was 47 μm, in which with the addition of 5 wt% B4C, the particle size decreased to 33 μm. The highest UTS (217 MPa) and El% (7%) was achieved in Al-20%Mg2Si-5%B4C hybrid composite. The cast Al-20%Mg2Si composite revealed the brittle mode of fracture with some cleavage characterization, in which with the addition of 5%B4C, the fracture mode altered to a more ductile fracture. The wear results revealed that the Al-20%Mg2Si-5%B4C hybrid composite has the highest wear resistance with the lowest wear rate (0.46 mm3/Km) and friction coefficient (µ = 0.52) under 20 N applied load compared to other fabricated composites with mild abrasion as the governed wear mechanism

The wettability enhancement of SiC particles in cast aluminum a356 matrix composites

A study has been conducted using compocasting technique to investigate the wettability enhancement of SiC in aluminum matrix composite. Aluminum matrix composite reinforced with SiC is produced by the addition of 1% Mg powder which have impact on a uniform distribution of SiC in the Aluminum matrix. In addition, it is worthwhile to mention that there is mutual relationship between a uniform distribution of SiC in the aluminum matrix and mechanical properties. The findings show that there are some important determinants, which have strong influence on a uniform distribution of SiC in the Aluminum matrix such as surface treatment of SiC, addition of alloy elements including Mg and other elements, particle size, percentage of Mg, stirring speed and stirring method and solidification rate. Among of mentioned determinants, the results show that addition of Mg into melt is the salient predictor. In addition, there is a direct relationship between mechanical properties and a uniform distribution of silicon carbide inside the aluminum matrix. Result from the mechanical testings and the microstructural show that the addition of 1% Mg improves the wettability of the aluminum/SiC composites

The wettability enhancement of SIC particles in cast aluminium A356 matrix composites

A study has been conducted using compocasting technique to investigate the wettability enhancement of SiC in aluminum matrix composite. Aluminum matrix composite reinforced with SiC is produced by the addition of 1% Mg powder which have impact on a uniform distribution of SiC in the Aluminum matrix. In addition, it is worthwhile to mention that there is mutual relationship between a uniform distribution of SiC in the aluminum matrix and mechanical properties. The findings show that there are some important determinants, which have strong influence on a uniform distribution of SiC in the Aluminum matrix such as surface treatment of SiC, addition of alloy elements including Mg and other elements, particle size, percentage of Mg, stirring speed and stirring method and solidification rate. Among of mentioned determinants, the results show that addition of Mg into melt is the salient predictor. In addition, there is a direct relationship between mechanical properties and a uniform distribution of silicon carbide inside the aluminum matrix. Result from the mechanical testings and the microstructural show that the addition of 1% Mg improves the wettability of the aluminum/SiC composites

A novel method to enhance the performance of an ex-situ Al/Si-YSZ metal matrix composite

A novel technique was used to synthesise an Al–Si/YSZ composite with improved bonding strength between the matrix and YSZ particles. Based on thermal analysis results, Bi was added in slurry state at 605 ± 5 °C, and two-step stirring was applied. It was found that the duration of mushy zone decreased and solidification rate increased with the addition of YSZ particles. Elemental mapping analysis on etched and deep-etched conditions revealed that these YSZ particles were surrounded by Bi. Mechanical characterisation showed that YS, UTS, El% and the hardness of the A356 + Bi/YSZ composite increased by 25.5%, 2%, 43% and 24% respectively. Fractography analysis confirmed that the interfacial bonding strength at Al/YSZ improved significantly with the addition of Bi. The wear rate and friction coefficient of A356 + Bi/YSZ decreased to 0.464 and 0.55 mm3/Km respectively, which are 34.6% and 6.7% lower than the values obtained for the A356/YSZ composite. The worn surface revealed mild abrasion wear mechanisms in the A356 + Bi/YSZ composite

Cooling curve thermal analysis of Al–Mg2Si–Cu–xSr composite

In situ composites are today being considered for industrial use, owing to the fewer production steps involved, lower production cost, and better wetting of reinforcements. This study emphasises the characteristic features of an Al–Mg2Si–Cu in situ composite, with the addition of different amounts of Sr (0.01–0.1 mass%) as a modifier reagent, by employing computer-aided cooling curve thermal analysis. The identification of microstructures and phases was carried out using a scanning electron microscope equipped with an energy dispersive spectrometer. The results show that the nucleation temperature of the primary Mg2Si, eutectic Mg2Si, and Al5FeSi phases initially increased with the addition of 0.01 mass% Sr, and subsequently decreased with further addition of the element. Two new Sr-containing phases were detected after the precipitation of primary Mg2Si phase and prior to the formation of eutectic Mg2Si phase. A relationship between the cooling rate (CR) and solidification rate (SR) was established. Based on cell coherency point, it was found that the eutectic Al–Mg2Si cell required a longer time to grow with the increment of Sr. The solid fraction of Al5FeSi and Al5Cu2Mg8Si6 + Al2Cu phases remained constant at 8 ± 1% and 3 ± 1%, respectively. The increase in the terminal freezing range and the cracking susceptibility coefficient, by 182% and 16%, respectively, shows that Sr increases the probability of hot tearing

Effect of hot extrusion on microstructural evolution and tensile properties of Al-15%Mg2Si-xGd in-situ composites

This study investigates the effect of hot extrusion on microstructure and tensile properties of Al–15 wt %Mg2Si in-situ composite in unmodified and modified with (0.5–5.0 wt %) Gd addition. Furthermore, the morphology evolution of primary and eutectic Mg2Si particles in both unmodified and modified with 1.0 wt % Gd prepared by hot extrusion were examined in detail. The results showed that hot-extrusion process was efficient in transforming truncated octahedral primary and rod-like eutectic Mg2Si particles into near spherical and dot-like morphology, respectively in the modified alloy in which the particle fragmentation and thermal disintegration are the main mechanisms responsible for refinement/modification of primary and eutectic Mg2Si particles. It was suggested that the alteration of Mg2Si particles as well as fragmentation of Gd intermetallic compounds (IMCs) by hot extrusion played a significant role in strengthening the composite, i.e., the ultimate tensile strength (UTS) and elongation (%) values increased from ∼224.62 MPa to 3.75% in the 1.0 wt % modified composite to ∼245.83 MPa and 7.65% in the extruded modified one, respectively. In fact, a higher fracture stress can be established by fine near spherical primary Mg2Si particles through impeding dislocation motions and freeing stress concentrations. Furthermore, fragmentation of eutectic Mg2Si and Gd (IMCs) after extrusion lead to enhancement in ductility. This study demonstrated that combination of Gd addition and hot extrusion is a promising approach in modifying the microstructure and enhancing the tensile properties of in-situ Al-15%Mg2Si composite for industrial applications