Abstract
Metal–metal composites represent a particular class of materials showing innovative mechanical and electrical properties. Conventionally, such materials are produced by severely plastically deforming two ductile phases via rolling or extruding, swaging, and wire drawing. This study presents the feasibility of producing metal–metal composites via a capacitive discharge-assisted sintering process named electro-sinter-forging. Two different metal–metal composites with CP-Ti/AlSi10Mg ratios (20/80 and 80/20 vol.%) are evaluated, and the effects of the starting compositions on the microstructural and compositional properties of the materials are presented. Bi-phasic metal–metal composites constituted by isolated α-Ti and AlSi10Mg domains with a microhardness of 113 ± 13 HV0.025 for the Ti20-AlSi and 244 ± 35 HV0.025 for the Ti80-AlSi are produced. The effect of the applied current is crucial to obtain high theoretical density, but too high currents may result in Ti dissolution in the Ti80-AlSi composite. Massive phase transformations due to the formation of AlTiSi-based intermetallic compounds are observed through thermal analysis and confirmed by morphological and compositional observation. Finally, a possible explanation for the mechanisms regulating densification is proposed accounting for current and pressure synergistic effects.
Highlights
Published: 17 October 2021Aluminum and Titanium alloys are widely used in automotive applications due to their specific properties
This study presents the feasibility of producing metal–metal composites via a capacitive discharge-assisted sintering process named electro-sinter-forging
As observed in previous research on Nitinol [17] and on a modified 100Cr6 [18], employing a rapid capacitive sintering process where powders are enclosed in a confined die helps hinder the reactivity of the processed powders with the environmental atmosphere
Summary
Aluminum and Titanium alloys are widely used in automotive applications due to their specific properties. Singh et al [3] summarized the possible techniques for developing metal–matrix composites: stir casting, centrifugal casting, squeeze casting, and powder metallurgy This latter is highly important for the production of net-shaped and near-net-shaped components [4]: it is a flexible manufacturing process capable of delivering a wide range of materials, producing high-quality complex parts to close tolerances in a cost-effective way [5]. By increasing the plasma spray sintering temperature, homogeneous Ti-Al intermetallicsbased alloys were obtained These multilayered Ti/Ti-Al intermetallics compacts exhibited very high flexural strength and toughness of 1400 MPa. In [11], Ti-Al3 Ti laminated composites have been prepared with Ti, using Al foils having different initial thicknesses. From a previous study on the cold rolling of an ESFed CuSn15 bronze [19], the authors observed the presence of non-alloyed domains constituted by pure Cu in the densified material as a side-effect of admixing pure Cu powders to the CuSn ones.
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