Evolution of near-equiaxed microstructure in the semisolid state

Aluminum (Al)-stainless steel 316L (SUS316L) composites were successfully fabricated by the spark plasma sintering process (SPS) using pure Al and SUS316L powders as raw materials. The Al-SUS316L composite powder comprising Al with 50 vol.% of SUS316L was prepared by a ball milling process. Subsequently, it was sintered at 630 °C at a pressure of 200 MPa and held for 5 min in a semisolid state. The X-ray diffraction (XRD) patterns show that intermetallic compounds such as Al13Fe4 and AlFe3 were created in the Al-SUS316L composite because the Al and SUS316L particles reacted together during the SPS process. The presence of these intermetallic compounds was also confirmed by using XRD, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and EDS mapping. The mechanical hardness of the Al-SUS316L composites was analyzed by a Vickers hardness tester. Surprisingly, the Al-SU316L composite exhibited a Vickers hardness of about 620 HV. It can be concluded that the Al-SUS316L composites fabricated by the SPS process are lightweight and high-hardness materials that could be applied in the engineering industry such as in automobiles, aerospace, and shipbuilding.

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On the Development of an Al4.8 wt% Cu Alloy Obtained from Recycled Aluminum Cans Designed for Thixoforming Process

Advances in Materials Science and Engineering ◽

10.1155/2016/6762109 ◽

2016 ◽

Vol 2016 ◽

pp. 1-8

Author(s):

Ronan Miller Vieira ◽

Gianni Ferreira Alves Moreira ◽

André Itman Filho ◽

Estéfano Aparecido Vieira

Keyword(s):

Solution Heat Treatment ◽

Natural Aging ◽

Tensile Tests ◽

Permanent Mold ◽

Semisolid State ◽

Globular Microstructure ◽

Cu Alloy ◽

Heat Treated ◽

Aluminum Cans ◽

Melting And Solidification

This work has focused on the development of a new aluminum alloy containing 4.8 wt% of Cu alloy obtained from recycled aluminium cans designed for thixoforming process. After the step of melting and solidification of the alloy in a metallic permanent mold, samples were solution heat treated at 525°C for times ranging from 2 h to 48 h, quenched in water and followed by natural aging. Results have shown the evolution of hardness so from them solubilization solution heat treatment was chosen for 24 h. The best condition for aging was 190°C during 3 h. With this data pieces were thixoforged at 580°C and 615°C corresponding, respectively, to solid fraction (fs) of 0.8 and 0.6. The optimized T6 temper was applied and tensile tests were performed. The mechanical properties obtained are compatible with those obtained for consolidated alloys processed in semisolid state (SS) and after T6 temper hardness increases from 95 HB to 122 HB and the best results were a tensile strength of 324 MPa ± 10 MPa, yield strength of 257 MPa ± 18 MPa, and an elongation of 7.1% ± 1%. For alloys designed for thixoforming process, these results are in accordance with what was expected whereas globular microstructure, high ductility, and good performance under cyclic conditions are desirable.

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Electromagnetic Stirring versus ECAP: Morphological Comparison of Al-Si-Cu Alloys to Make the Microstructural Refinement for Use in SSM Processing

Advances in Materials Science and Engineering ◽

10.1155/2016/9789061 ◽

2016 ◽

Vol 2016 ◽

pp. 1-7 ◽

Cited By ~ 3

Author(s):

Luis Vanderlei Torres ◽

Luis Fernando Torres ◽

Eugênio José Zoqui

Keyword(s):

Equal Channel Angular Pressing ◽

Morphological Evolution ◽

Direct Chill ◽

Solid Particles ◽

Electromagnetic Stirring ◽

Semisolid State ◽

Morphological Comparison ◽

Globular Structure ◽

Cross Sectional ◽

Angular Pressing

This work evaluates the morphological evolution at the semisolid state of the Al-4.0wt%Si-2.5wt%Cu alloy produced by direct chill casting under electromagnetic stirring (EMS) and by one equal channel angular pressing (ECAP) pass. The ECAP emerged as a promising technique capable of reduction and homogeneous metals microstructure imposing large deformations occurs in a matrix that contains two channels of the same cross-sectional area and forms an angle of 120°. The materials were submitted to reheating treatment in condition of 60% solid fraction at treatment times of 0, 30, and 90 s. Comparing the two cases, we have the presented ECAP process that had an excellent response to the recovery and recrystallization mechanisms, and refined microstructures ideal for thixoforming were produced. Primary particle sizes of about 45 μm and grain sizes of about 75 μm and a circularity shape factor of more than 0.60 were obtained. The low silicon alloy, Al-4.0wt%Si-2.5wt%Cu, presented excellent refinement when processed via equal channel angular pressing, presenting good morphological stability at the semisolid state, without significant changes in size or shape of the solid particles. This fully globular structure is favourable for thixoforming processes.

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