Sandeep Panyam Rajagopal a , Rajesh Gandasi Lakshmikantha a , Auradi Virupaxi a , Kori Shivputrappa Amarappa b a Research and Development Centre, Department of Mechanical Engineering, Siddaganga Institute of technology, Tumkur, Karnataka, India b Research and Development Centre, Department of Mechanical Engineering, Basaveshwara College of Engineering, Bagalkot, Karnataka, India Influence of ceramic B 4 C particulate addition on tensile behavior of 6061 aluminum matrix Paper presented at \International Conference an Advances in Design & Manufacturing" (ICAD&M14), 5 – 7 December 2014, National Institute of Technology, Tiruchirappalli, Tamil Nadu, India In this study, an attempt was made to prepare 6061Al – B 4 C p composites through a two-step melt stirring process at 750 8C. During the preparation of the composite, pre- heated K 2 TiF 6 flux along with B 4 C p (ratio 0.08) was added in the melt in two steps to avoid segregation of B 4 C P . Microstructural characterization was done using scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction techniques. Density, hardness and tensile strength of the cast alloy and the composite were de- termined both at room temperature and 100 8C. Fracture studies of the tensile specimens were also done using scan- ning electron microscopy. Keywords: Fractography; High temperature strength; Mi- crostructure; Orowan mechanism; Slip systems 1. Introduction Metal matrix composites (MMCs) have attracted consider- able interests in the aircraft industry and automobile sector because a combination of their unique properties such as light weight, low coefficient of thermal expansion, and low density [1 – 5]. Aluminum is preferred as a matrix ma- terial in MMCs because of its low density, easy fabricabil- ity and good engineering properties. Among the various aluminum alloys, heat treatable 6061aluminum (6061Al) has been extensively explored. This alloy is highly corro- sion resistant and exhibits moderate strength and finds many applications in construction, automotive, and marine fields. Boron carbide particulates (B 4 C P ) have been em- ployed for reinforcement due to their good chemical and thermal stability. B 4 C P has lower density and higher hard- ness compared to Al 2 O 3 and SiC [6, 7]. Lee et al. [8] inves- tigated the effect of reinforcement type on the tensile prop- erties of the Al–B 4 C P and Al – SiC composites and observed that the strength of Al – B 4 C P composites is great- er than that of the Al – SiC composites. But higher cost and lower wettability of B 4 C P limit its applications. Halverson et al. [9] reported that the processing problems and mechan- ical property limitations can be significantly reduced by in- troducing B 4 C P cermet. It is also proposed that addition of degassing capsules (about 4 g) decreases the porosity which in turn improve the tensile strength. K 2 TiF 6 flux addition increases the incorporation behavior of B 4 C P with 6061Al. Kennedy and Brampton [10] suggested that apart from wet- ting, control of the interfacial reaction at 6061Al – B 4 C P in- terface is also important in the production of cast 6061Al – B 4 C P composites. Halverson et al. [11] observed that tita- nium is one of the reactive metals that can be used to in- crease wettability in 6061Al – B 4 C P system. TiC and TiB 2 layers are formed on the surfaces of boron carbide in 6061Al – B 4 C P composites due to the high chemical affinity of titanium to boron. TiC and TiB 2 act as a reaction barrier and restrict the undesirable interfacial reactions that can occur at the interface. It is quite challenging to obtain a homogeneous dispersion of reinforcement. Porosity, size, and distribution are very important in controlling the me- chanical properties of metal matrix composites. The tensile testing of aluminum matrix composites has been widely studied. It is well known that hard B 4 C P enhances the ten- sile strength more compared to the matrix alone. The tensile strength of a composite material depends on gauge length, particle size, particle homogeneity and chemical composi- tion of matrix material. In addition, a dependence of tensile failure on the distribution of reinforcements (particularly clustering and particle size) has been observed [12 – 15]. The present work on 6061Al – B 4 C composite is a re- search project of the Aeronautical Research and Develop- ment Board. The work proposed in this project includes de- veloping a product out of composite by optimizing the process parameters. Further, the main concentration of the work is to produce 6061Al – B 4 C composite at lower tem- peratures (less than 800 8C) because of poor wettability of B 4 C by Al matrix at temperatures below 800 8C. Volume fraction and size of the B 4 C particles are the two parameters to be optimized along with other parameters. Considering this, volume fractions of the B 4 C particles chosen were 5, 7, 9 and 12 and sizes of the B 4 C particles selected were i) Sandeep P. R. et al.: Influence of ceramic B 4 C particulate addition on tensile behavior of 6061 aluminum matrix Int. J. Mater. Res. (formerly Z. Metallkd.) 107 (2016) 5 439 International Journal of Materials Research downloaded from www.hanser-elibrary.com by Hanser Verlag (Office) on May 12, 2016 For personal use only.