Contents lists available at ScienceDirect Materials Characterization journal homepage: www.elsevier.com/locate/matchar Hot deformation flow behavior of powder metallurgy based Al-SiC and Al- Al 2 O 3 composite in a single step and two-step uni-axial compression Kanhu Charan Nayak ⁎ , Prashant P. Date Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India ARTICLE INFO Keywords: Dynamic recovery Metal matrix composite Flow stress Friction Recrystallization Work hardening ABSTRACT The material flow behavior of aluminium metal matrix composites at a high-temperature is required to manu- facture the forged components for the lightweight application. In this study, four varieties of aluminium based composites such as Al/3 vol%SiC, Al/7 vol%SiC, Al/3 vol%Al 2 O 3 and Al/7 vol%Al 2 O 3 composites were synthe- sized using powder metallurgy route. Single step deformation was performed at 500 °C to get a true unity strain at strain rates of 10/s -1 and 20s -1 . In two-step, the first deformation was at 500 °C followed by additional deformation at 430 °C at strain rates of 10s -1 and 20s -1 . The compression test results show the Al/7 vol% SiC composite exhibit comparatively higher value of peak true stress (46.36 MPa at a strain rate of 20s -1 ) at a temperature of 500 °C in single step deformation. The interface coefficient of friction between anvils and spe- cimen decreased with increase in strain rate. Electron backscatter diffraction (EBSD) maps revealed that, Al/ 7 vol% SiC p and Al/7 vol% Al 2 O 3p shows partially dynamically recrystallized grains at the interface of alumi- nium and the particulate reinforcements (SiC and Al 2 O 3 ) under a strain rate of 10s -1 . Subgrain boundaries with dynamic recovery grains were observed in aluminium when it was deformed at strain rates of 10 s -1 and 20 s -1 to a true strain of 0.6. In the view of flow stress and evolution of microstructures, this investigation provides insight into the implementation of the forging process for aluminium metal matrix composite. 1. Introduction Metal matrix composite (MMC) is a homogeneous mixture of two or more chemically distinct and insoluble phases so that one serves as the matrix and the other as reinforcement. MMC provides a synergistic combination of mechanical and physical properties that cannot be achieved in monolithic metal alloys. These composite materials ob- tained by incorporating reinforcement particles such as SiC, Al 2 O 3 ,B 4 C or AlN into low density and ductile aluminium alloys [1–3] are the favored to replace conventional materials in many applications. Particulate-reinforced aluminium metal matrix composites having SiC and alumina are widely used in the automobile industry and aerospace industry due to high specific strength retained at higher temperature [4–7]. The lightweight materials play an important role in the automotive industry for energy saving [2,8]. The automobile en- gines consume energy to overcome the inertia of reciprocating masses. The inertia of reciprocating masses consists of the mass of connecting rod and piston with the piston pin. These reciprocating parts are de- signed in such a way as to take the dynamic or fluctuating loads under different temperature conditions developed inside the cylinder of the internal combustion engine. The piston in the engine is made from an AleSi alloy. Reciprocating parts of internal combustion engines are usually manufactured using aluminium (piston) and steel/Aluminium by casting or forging processes (both cold and hot forging). In service, a piston is subjected to large impact loading (due to pressure pulses oc- curring several thousand times a minute) at high temperature and hence, creep loading at high temperature. Therefore, it is important to understand the effect of ceramic particles in aluminium, on its high- temperature mechanical behavior. Several manufacturing methods have so far been adopted to pro- duce the Al-SiC composites in an attempt to address cost and manu- facturability. These include stir casting, squeeze casting, pressure https://doi.org/10.1016/j.matchar.2019.03.047 Received 18 January 2019; Received in revised form 20 March 2019; Accepted 31 March 2019 Abbreviations: ε, true strain; σ, true stress, MPa; ε ̇ , strain rate, /s; H i , initial specimen height, mm; D i , initial diameter of specimen, mm; H f , final height of specimen, mm; A i , initial cross-section of specimen, mm 2 ; F, applied compressive load, N; D, ideal diameter, mm; D max , maximum diameter, mm; ϕ, degree of barreling; μ, coefficient of friction; b f , barreling factor; I, aluminium; II, Al/3 vol% Al 2 O 3p ; III, Al/7 vol% Al 2 O 3p ; IV, Al/3 vol% SiC p ; V, Al/7 vol% SiC p ; σ MMC /σ I , flow stress of composite materials to flow stress of aluminium; σ II /σ I , flow stress of Al/3 vol% Al 2 O 3p to flow stress of aluminium; σ III /σ I , flow stress of Al/7 vol% Al 2 O 3p to flow stress of aluminium; σ IV /σ I , flow stress of Al/3 vol% SiC p to flow stress of aluminium; σ V /σ I , flow stress of Al/7 vol% SiC p to flow stress of aluminium ⁎ Corresponding author. E-mail address: nayakkanhu83@gmail.com (K.C. Nayak). Materials Characterization 151 (2019) 563–581 Available online 01 April 2019 1044-5803/ © 2019 Elsevier Inc. All rights reserved. T