M.K. Surappa

Bio: M.K. Surappa is an academic researcher from Indian Institute of Science. The author has contributed to research in topics: Microstructure & Particle. The author has an hindex of 29, co-authored 67 publications receiving 4010 citations. Previous affiliations of M.K. Surappa include Indian Institute of Technology Ropar & Anna University.

Aluminium matrix composites: Challenges and opportunities

Abstract: Aluminium matrix composites (AMCs) refer to the class of light weight high performance aluminium centric material systems. The reinforcement in AMCs could be in the form of continuous/discontinuous fibres, whisker or particulates, in volume fractions ranging from a few percent to 70%. Properties of AMCs can be tailored to the demands of different industrial applications by suitable combinations of matrix, reinforcement and processing route. Presently several grades of AMCs are manufactured by different routes. Three decades of intensive research have provided a wealth of new scientific knowledge on the intrinsic and extrinsic effects of ceramic reinforcement vis-a-vis physical, mechanical, thermo-mechanical and tribological properties of AMCs. In the last few years, AMCs have been utilised in high-tech structural and functional applications including aerospace, defence, automotive, and thermal management areas, as well as in sports and recreation. It is interesting to note that research on particle-reinforced cast AMCs took root in India during the 70’s, attained industrial maturity in the developed world nd is currently in the process of joining the mainstream of materials. This paper presents an overview of AMC material ystems on aspects relating to processing, icrostructure, roperties and applications.

Preparation and properties of cast aluminium-ceramic particle composites

Abstract: A casting technique for preparing aluminium-alumina, aluminium-illite and aluminium-silicon carbide particle composites has been developed. The method essentially consists of stirring uncoated but suitably heat-treated ceramic particles of sizes varying from 10 to 200 μm in molten aluminium alloys (above their liquidus temperature) using the vortex method of dispersion of particles, followed by casting of the composite melts. Recoveries and microscopic distribution of variously pretreated ceramic particles in the castings have been reported. Mechanical properties and wear of these composites have been investigated. Ultimate tensile strength (UTS) and hardness of aluminium increased from 75.50 MN m−2 and 27 Brinell hardness number (BHN) to 93.15 MN m−2 and 37 BHN respectively due to additions of 3 wt % alumina particles of 100 μm size. As a contrast, the tensile strength of aluminium-11.8 wt % Si alloy decreased from 156.89 MN m−2 to 122.57 MN m−2 due to the addition of 3 wt % alumina particles of the same size. Adhesive wear rates of aluminium, aluminium-11.8 wt % Si and aluminium-16 wt % Si alloys decreased from 3.62×10−8, 1.75×10−8 and 1.59×10−8 cm3 cm−1 to 2.0×10−8, 0.87×10−8 and 0.70×10−8 cm3 cm−1, respectively, due to the additions of 3 wt % alumina particles.

Fabrication and characterisation of pure magnesium-30 vol.% SiCP particle composite

Abstract: Pure magnesium-30 Vol.% SiC particle composite are fabricated by melt stir technique without the use of a flux or protective inert gas atmosphere. After hot extrusion with an extrusion ratio of 13, Mg-30 vol.% $SiC_P$ composites have been evaluated for their tensile properties at room and elevated temperatures (up to 400°C). Composites in the as-cast conditions do not show any change in dendrite arm spacing:cell size compared to unreinforced pure magnesium. However, in the extruded conditions average grain size of the composites is 20 mm compared to 50 mm in the pure magnesium. Microstructure shows no evidence of reaction product at particle:matrix interface. At room temperature, stiffness and UTS of the extruded composites are 40 and 30% higher compared to unreinforced pure magnesium, signifying significant strengthening due to the presence of the SiC particles. Further, up to temperatures of 400°C, composites exhibit higher UTS compared to pure magnesium. Mg composites show a wear rate lower by two orders of magnitude compared to pure Mg, when tested against steel disc using pin-on disc machine.

Particle reinforced aluminium and magnesium matrix composites

Abstract: Particle reinforced metal matrix composites are now being produced commerically, and in this paper the current status of these materials is reviewed. The different types of reinforcement being used, together with the alternative processing methods, are discussed. Depending on the initial processing method, different factors have to be taken into consideration to produce a high quality billet. With powder metallurgy processing, the composition of the matrix and the type of reinforcement are independent of one another. However, in molten metal processing they are intimately linked in terms of the different reactivities which occur between reinforcement and matrix in the molten state. The factors controlling the distribution of reinforcement are also dependent on the initial processing method. Secondary fabrication methods, such as extrusion and rolling, are essential in processing composites produced by powder metallurgy, since they are required to consolidate the composite fully. Other methods, suc...

Aluminium matrix composites: Challenges and opportunities

Abstract: Aluminium matrix composites (AMCs) refer to the class of light weight high performance aluminium centric material systems. The reinforcement in AMCs could be in the form of continuous/discontinuous fibres, whisker or particulates, in volume fractions ranging from a few percent to 70%. Properties of AMCs can be tailored to the demands of different industrial applications by suitable combinations of matrix, reinforcement and processing route. Presently several grades of AMCs are manufactured by different routes. Three decades of intensive research have provided a wealth of new scientific knowledge on the intrinsic and extrinsic effects of ceramic reinforcement vis-a-vis physical, mechanical, thermo-mechanical and tribological properties of AMCs. In the last few years, AMCs have been utilised in high-tech structural and functional applications including aerospace, defence, automotive, and thermal management areas, as well as in sports and recreation. It is interesting to note that research on particle-reinforced cast AMCs took root in India during the 70’s, attained industrial maturity in the developed world nd is currently in the process of joining the mainstream of materials. This paper presents an overview of AMC material ystems on aspects relating to processing, icrostructure, roperties and applications.