Synthesis, characterization and mechanical properties of in-situ (TiC-TiB 2 ) reinforced magnesium matrix composite B.N. Sahoo, S.K. Panigrahi ⁎ Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India HIGHLIGHTS • A novel method has been adopted to fabricate in-situ TiC-TiB 2 reinforced magnesium matrix hybrid composites. • The novel method is proven to develop such in-situ hybrid composite without addition of a third phase metal powder. • The in-situ reaction mechanism has been established. • A homogenization treatment has been implemented to the in-situ composites to enhance the strength and ductility. GRAPHICAL ABSTRACT abstract article info Article history: Received 16 May 2016 Received in revised form 3 July 2016 Accepted 6 July 2016 Available online 07 July 2016 Cast magnesium-metal matrix composites are widely used in automotive and aerospace industries due to high strength-to-weight ratio and good damping properties. In the present work, a novel hybrid method has been adopted to fabricate TiC-TiB 2 reinforced magnesium matrix composites. The reinforcement is formed in-situ from elemental Ti and B 4 C powders and molten Mg-Al-Zn alloy without any addition of a third phase metal pow- der such as aluminum. Results show that the distribution of TiC and TiB 2 reinforcing phases in the magnesium matrix is more uniform when the composite is fabricated at 900 °C for 2 h. The base and composite materials were subjected to homogenization treatment which resulted in dissolution of β-Mg 17 Al 12 phase into α-Mg ma- trix and enhances the strength and ductility by 22% and 50% in base and 17% and 50% in composite respectively. The enhancement of mechanical properties in the homogenized in-situ composites is explained in detail by an- alyzing the fractographs and microstructures of the material. © 2016 Elsevier Ltd. All rights reserved. Keywords: AZ91 magnesium alloy In-situ reaction Homogenization Mechanical properties Fractography 1. Introduction The demand of magnesium alloys are progressively increasing in the field of engineering applications due to their high specific stiffness and strength, low density, excellent damping capacity, good recycling ca- pacity and good machinability [1]. Magnesium and its alloys are about 35% lighter than aluminum alloys and over four times lighter than iron and steel. Its melting temperature is 650 °C and it crystallizes into a hexagonal close-packed (HCP) crystal structure. Because of the HCP structure these alloys have some limitations such as low room temper- ature ductility, poor formability and yield strength anisotropy. The stiff- ness, strength properties and wear resistance of these alloys are also low. The wear resistance, stiffness and strength of these alloys can be enhanced by reinforcing hard and thermally stable particles in the mag- nesium matrix via ex-situ and in-situ processing routes [2–4]. Materials and Design 109 (2016) 300–313 ⁎ Corresponding author. E-mail address: skpanigrahi@iitm.ac.in (S.K. Panigrahi). http://dx.doi.org/10.1016/j.matdes.2016.07.024 0264-1275/© 2016 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Materials and Design journal homepage: www.elsevier.com/locate/matdes