Charakterystyka właściwości kompozytu AK52/SiC uzyskanego metodą impulsowo-plazmowego spiekania

Prezentowane wyniki obejmują badania strukturalne, pomiary twardości i mikrotwardości oraz badania wytrzymałości na ściskanie kompozytu AK52/SiC otrzymanego metodami metalurgii proszków. Materiał wyjściowy wytworzono z wiór stopu AK52 (AlSi5Cu2) z dodatkiem węglika krzemu (SiC) w procesie mechanicznej syntezy. Uzyskano drobnoziarnisty proszek o jednorodnym rozmieszczeniu twardych cząstek ceramicznych w osnowie aluminium. Proces konsolidacji przeprowadzono metodą impulsowo-plazmowego spiekania, co w krótkim czasie pozwoliło otrzymać wypraski o dobrych właściwościach mechanicznych i jednorodnej strukturze. Dodatek twardych cząstek SiC powoduje wzrost twardości i wytrzymałości wytworzonych próbek. Analiza strukturalna potwierdziła jednorodną strukturę i drobnoziarnistość otrzymanych wyprasek.

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The paper presents investigations on possibility of using powder metallurgy processing for producing a composite structure, obtained by introducing SiC into recycled aluminium alloy by means of spark plasma sintering. The mixtures of SiC (0 and 20 wt% ) particles and AK52 (AlSi5Cu2) aluminum alloy chips were subjected to mechanical alloying throughout 40 hours. This lead to homogenous composite powder with particle size of about 3 mm, granular shape and uniform distribution of reinforcement particles into aluminum matrix. Higher amount of silicon carbide and longer time of processing allow to obtain a final overall microhardness of about 500 HV0.025. This is basically due to the strain hardening effect during MA and to the achievement of an homogeneous distribution of reinforcement in the composite powder. The prepared and identified powder mixtures (AK52+ (0 and 20 wt%) SiC) were finally densified by the spark plasma sintering method. The powders were embedded into the matrix with graphite cover and sintered at 450 [degrees]C, under 32 MPa by 5 min. The porosity investigations show that the AK52+20SiC consolidated compact was fully densified under these consolidation conditions while powders without addition of SiC has higher porosity results. The microstructure of compacted powders was examined by scanning electron microscopy (SEM) and light optical microscopy and reveals uniform structure of sintered composite powder. The Vickers hardness (HV5) tests increases with the addition of SiC particles. Hardness is a property related to the material resistance against plastic deformation which was confirmed by compression test. Content of SiC addition allows to increase stress but ductility of composite samples is still very low. Spark plasma sintering process is an effective consolidation method to obtain dense AK52/SiC composites with homogeneous structure and advanced mechanical properties.