Influence of Cu content on microstructure and mechanical properties of thixoformed Al−Si−Cu−Mg alloys

The effects of Cu content on the microstructure and mechanical properties of thixoformed Al−6Si−хCu−0.3Mg (х= 3, 4, 5 and 6, mass fraction, %) alloys were studied. The samples were thixoformed at 50% liquid content and several of the samples were treated with the T6 heat treatment. The samples were then examined by optical microscopy (OM), scanning electron microscopy(SEM), energy dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) analysis, as well as hardness and tensile tests. The results show that the cooling slope casting and thixoforming process promote the formation of very fine and well distributed intermetallic compounds in the aluminium matrix and the mechanical properties of the alloys increase considerably compared with the permanent mould casting. The results also reveal that as the Cu content in the alloy increases, the hardness and tensile strength of the thixoformed alloys also increase. The ultimate tensile strength, yield strength and elongation to fracture of the thixoformed heat-treated Al−6Si−3Cu−0.3Mg alloy are 298 MPa, 201 MPa and 4.5%, respectively, whereas the values of the thixoformed heat-treated alloy with high Cu content (6%) are 361 MPa, 274 MPa and 1.1%, respectively. The fracture of the thixoformed Al−6Si−3Cu−0.3Mg alloy shows a dimple rupture, whereas in the alloy that contains the highest Cu content (6%), a cleavage fracture is observed

The effects of mg addition on the microstructure and mechanical properties of Thixoformed Al-5%Si-Cu alloys

In this study, the effects of different amounts of magnesium (Mg) on the microstructures and tensile properties of thixoformed Al–5%Si–Cu alloys were investigated. Three different alloys containing various amounts of Mg (0.5, 0.8 and 1.2 wt%) were prepared through the cooling slope casting technique, before they were thixoformed using a compression press. Several of the thixoformed samples were then treated with a T6 heat treatment, that is, solution treatment at 525 C for 8 h, quenching in warm water at 60 C, followed by aging at 155 C for 4 h. All of the samples were then characterised by optical microscopy (OM), scanning electron microscopy (SEM) energy dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) analysis as well as by tensile tests. The results revealed that magnesium was able to refine the size of a-Al globules and the eutectic silicon in the samples. It was also observed that a compact p-Al9FeMg3Si5 phase was formed when the magnesium content was 0.8 wt% and 1.2 wt%. The mechanical properties of the thixoformed alloys improved significantly after the T6 heat treatment. The highest attainment was recorded by the latter alloy (i.e. with 1.2 wt%Mg) with its ultimate tensile strength (UTS) as high as 306 MPa, yield strength (YS), 264 MPa, and elongation to fracture of 1.8%. The fracture of thixoformed alloy with a low Mg content (0.5 wt%) showed a combination of dimple and cleavage fracture, whereas in the alloy that contained the highest Mg content (1.2 wt%), cleavage fracture was observed

Trust Force And Hole Quality Observation In Various Major Penetration Angle Drilling Of Carbon Fibre Reinforced Plastic (CFRP)

This paper has presented a new approach to study the comparison of thrust force and hole quality observation for three types of the drill with penetration angle of 0°, 15° and 30° for drilling carbon fibre reinforced plastic (CFRP) laminates. The experimental approach is adapting to a combination of the design of experiment Taguchi’s technique and analysis of variance (ANOVA). The drill types involved in the experiment are twist drill, dagger drill and straight flute drill. Plan of experiments adopted on the Taguchi technique with variable cutting parameters of drill types, drilling penetration angle, spindle speed and feed rate was performed in drilling autoclave carbon fibre reinforced plastic (CFRP) laminates. Based on the statistical experiment results, lower feed rate and lower penetration angle contribute lower thrust force at constant spindle speed operation for the twist, dagger and straight flute drill type based on response surface graph analysis in order of Taguchi design method. In term of hole quality observation, hole drilled with straight flute drill has the best hole quality compared with other drill types in this experiment. Drilling penetration angle contributes significant contribution to drilling thrust force and drilled hole quality

An overview of semisolid processing of aluminium alloys

Semisolid metal processing (SSM) or thixoforming is a new technology that offers several advantages over liquid processing and solid processing. This process utilizes semisolid behavior as well as reduces macrosegregation, porosity, and forming forces during shaping process. A lot of research work has been carried out by various researchers in order to exploit the potential of this process to produce different products especially for automotive industry. This paper will summarise the rheological behavior of aluminium alloys in semisolid slurries, thixoformability of modified aluminium alloys, the effect of feedstock production method on mechanical properties, and the importance of developing low-cost raw materials for semisolid processing

Effects Of Mechanical Stirring And Short Heat Treatment On Thixoformed Of Carbon Nanotube Aluminium Alloy Composite

The present work aimed to determine the effects of thixoforming and short T6 heat treatment processes on the microstructure and mechanical properties of thixoformed A356 alloy reinforced with 0.5 wt% multi-walled carbon nanotube (A356-MWCNT). The semisolid composite feedstock was produced by a mechanical stirring route followed by thixoforming, and finally, it was heat treated with a shorter solution treatment and artificial ageing hours. A premix of 0.5 wt% magnesium (Mg) as wettability agent and MWCNT was injected into molten A356 alloy at 650 °C. Mixing and stirring were performed by a using three-blade impeller at 500 rpm for 10 min, and the mixture was poured into a preheated mould. Microstructure studies show the mechanical stirring effects on the transformation of dendritic arms to mostly globular and rosette structures of α-Al. The formations of more spheroidised structure of eutectic silicon (Si) were predominant after the heat treatment, thereby revealing the effectiveness of shorter T6 heat treatment. Results of field emission scanning electron microscopy images showed uniform distribution and pull-out structures of MWCNT throughout the matrix, thereby justifying the effective load transfer and wettability between reinforcement and alloy matrix. Subsequently, the mechanical properties of the composite shown significant improvements after each stage. The yield strength (YS), ultimate tensile strength (UTS) and elongation to fracture of cast A356 alloy increased from 115 MPa, 132.9 MPa and 1.8% to 135 MPa, 178.3 MPa and 3.1% respectively, in the A356-MWCNT. Consequently, these properties were further improved to 180 MPa, 255.8 MPa and 5.7% after the thixoforming process. The highest attainment of yield strength (YS), ultimate tensile strength (UTS) and elongation to fracture after short T6 of A356-MWCNT were 215 MPa, 277.0 MPa and 7.6%, respectively. The hardness of the samples was improved from 59.5 HV in as-cast alloy to 106.4 HV in thixoformed short T6 A356-MWCNT

Homogenous Dispersion And Interfacial Bonding Of Carbon Nanotube Reinforced With Aluminum Matrix Composite: A Review

Recent developments in the field of carbon nanotube (CNT) have attracted attentions on a new development of aluminum matrix composite (AMC). Homogenous dispersion and interfacial bonding of CNT/metal matrix are the two main problems yet to have sound solutions.In general, to ensure uniform dispersion, the overall process can be divided into three steps: preprocessing, mixing and post processing. This paper summarizes previousworks on solid and liquid processing techniques which some are more successful than others by looking at the improvement of the composite tensile strengths. On the other hand the interfacial bonding depends on the existance of Al4C3 phase and physical conditions of CNT. Both elements must be controlled for the optimized results. The review presented here would be used as references in the future works to fabricate higher strength CNT/aluminum composite

Study On Mechanical Properties And Microstructure Analysis Of Aisi 304l Stainless Steel Weldments

Manufacturing operations require joining process in a way that it is considered as an important process to be applied in almost every operation or process that involves fabricating of products. The aim of this research is to evaluate mechanical properties and analyzed Heat Affected Zone (HAZ) of austenic stainless steel AISI 304Lweldments. The welding was conducted based on three different sizes of filler wire 0.8mm, 1.0mm and 1.2mm respectively. The arc voltage used also consists of three different values 30V, 60V and 90V and the current flow for Metal Inert Gas (MIG) welding was set to constant value of 100A. The specimens were divided into five groups to undergo tensile test, hardness test, impact test, HAZ temperature variation study and followed by microstructure observation. The experimental result showed that tensile strength, hardness and impact resistance were increased with the used of biggest size of filler wire which is 1.2 mm. The relations then were compared with HAZ temperature variation analysis and the image analyzer showed that the transformation from austenite to martensite at HAZ created a hard and brittle structure near the fusion zone. The results revealed that different filler wire size and different arc voltage applied could enforce the austenitic stainless steel structure

Determination of the chromosome number and genome size of Garcinia mangostana L. via cytogenetics, flow cytometry and k-mer analyses

Mangosteen (Garcinia mangostana L.) is one of the most popular tropical fruit of South-East Asia. It has considerable economic potential for local and export markets. This paper describes a research work to determine the number of chromosomes and genome size of G. mangostana through chromosome counting, flow cytometry and k-mer analyses. Chromosome count analysis revealed that the chromosome number of G. mangostana varied from 74 to 110. The high number observed could be due to the occurrence of mutation and aneuploidy in G. mangostana. Using flow cytometry with Glycine max cv. Polanka (2C = 2.5 pg) used as standard, G. mangostana genome size was found to be 2C = 6.00 ± 0.17 pg. Meanwhile, a genome survey of G. mangostana was performed using Illumina HiSeq 2000 DNA sequencing; k-mer analysis revealed that the genome size of G. mangostana was approximately 5.92 Gbp, or approximately 6.05 pg (1 pg DNA = 0.9780 × 109 bp). Based on the flow cytometry and genome survey, the study concludes that the genome size of G. mangostana is between 6.00 and 6.05 pg