1,721,115 research outputs found
Effect of aging on fracture toughness parameters and tensile properties of 17-4 PH stainless steel
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Mechanical and Impact Behaviour of (Al2O3)P/2014 and (Al2O3)P/6061 Al Metal Matrix Composites in the 25-200 °C Range
No full textThe present work is aimed at studying the impact behaviour of commercially available Aluminum matrix composites, in a temperature interval ranging from 25 °C to 200 °C. The results of instrumented impact tests and of microstructural and fractographic observations are correlated with the tensile properties of these materials. A description of the phenomena involved (particles cracking, interfacial failure associated to matrix-reinforcement reaction layers, ductile behaviour of the matrix) is given. The effect of testing temperature as well as that of the matrix characteristics are presented and discussed
Sliding behaviour of nanophased AISI M2 tool steel obtained by mechanomaking and hot isostatic pressing
No full textWear properties of Fe - Fe 3 C nanophase white iron obtained by mechanosynthesis and hot isostatic pressing
No full textHigh strain rate superplasticity in aluminum matrix composites
No full textRecently, several studies have demonstrated that a variety of metallic materials, including aluminium-based composites, can exhibit superplasticity at relatively high strain rates (≥10-2s-1). High strain rate superplasticity (HSRS) is very attractive for commercial applications, mainly for materials difficult to shape or machine with conventional techniques, such as metal matrix composites. In this work, the possibility of achieving HSRS in a recently developed composite with an AA6013 matrix reinforced with about 20 vol % of SiC particles (AA6013/20/SiCp) was studied. Uniaxial tensile tests were carried out at high strain rates (1 x 10-1s-1 and 1 x 10-2s-1) and in a temperature range between 520 and 590°C. A maximum elongation-to-failure of 370 per cent was obtained at 560°C with a strain rate of 1 x 10-1s-1. This temperature is very close to the temperature at which melting of the composite starts. Scanning electron microscopy (SEM) analyses of fracture surfaces in the optimum superplastic condition showed the presence of filaments, the formation of which generally related to the presence of a liquid phase at the grain boundaries and/or at the interfaces
RASSEGNA CRITICA DELLE TECNICHE DI PRODUZIONE DI MATERIALI COMPOSITI A MATRICE METALLICA
No full textIn questo lavoro sono sistematicamente presentate le diverse tecnologie produttive di materiali compositi a matrice metallica, con particolare riferimento a quelli a matrice in lega di alluminio. Partendo dalla suddivisione classica, tra metodi in liquido e in solido, tali tecnologie vengono descritte in termini di:
- schematizzazione dei principi del processo,
- caratteristiche principali dei compositi ottenibili,
- applicazioni industriali
Friction and Wear of Aluminum Alloys and Composites
No full textThe chapter starts with an overview on Al alloys and Al-based composites, presenting their physical and mechanical properties, designation, effects of the main alloying elements, microstructural features of cast and wrought Al alloys, strengthening mechanisms and heat treatments. Subsequently the tribological behavior of Al alloys and Al-based composites is presented and discussed, focusing on the dry sliding wear and discussing the effects of: material-related parameters (silicon content, size and shape; other alloying elements and role of intermetallic particles); main operating conditions (load, sliding speed, temperature). Wear maps for Al-Si alloys and MMCs are also reported
Studio del contatto bronzo-acciaio in condizioni di strisciamento nel settore delle macchine automatiche (Bronze-steel sliding contact in packaging applications)
No full textLo studio condotto è dedicato a componenti di macchine automatiche per la pressatura di polveri ad uso farmaceutico o alimentare, sottoposti ad un contatto tribologico non conforme di strisciamento in condizioni di lubrificazione limite. Il tribosistema studiato comprende due elementi: punzoni in acciaio da utensili X100CrMoV5 e camme in bronzo all’alluminio G-CuAl11Fe4Ni4. Nella fase iniziale dello studio sono stati identificati i meccanismi di usura prevalenti nel tribosistema reale avvalendosi di tecniche standard di failure analysis, mentre nella seconda fase sono state eseguite prove di strisciamento su scala di laboratorio. Nelle prove tribologiche di laboratorio, il coefficiente di attrito è risultato indipendente dalle condizioni di trattamento termico del bronzo, mentre si è rilevata una significativa dipendenza da carico normale e velocità. L’usura del bronzo è risulta principalmente influenzata dalla sua capacità di incrudimento e/o di formare e stabilizzare uno strato protettivo superficiale a base di ossidi di rame, al variare delle condizioni di trattamento termico e dei parametri operativi del moto
Microstructural modifications associated with the superplastic flow of the aluminium alloy 7475
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