The present work aims to study the individual as well as the combined effect of in-situ particles and precipitates on the tension-compression asymmetricity of AZ91 magnesium (Mg) alloy and AZ91 + TiC-TiB2 Mg matrix composites. Investigations have been done on four different material conditions: (a) alloy without particles or precipitates, (b) alloy with precipitates, (c) composite with particles, (d) composites with both particles and precipitates. Both the particle and precipitate significantly contribute towards lowering of tension to compression yield asymmetry. These particles/precipitates increase the critical stress for twinning by exerting a back stress which hinders the twin propagation. Due to decrease in the twinning propensity, the tension to compression asymmetry reduces from 1.30 (at base condition) to 1.04 (peak aged condition of the composite). This phenomenon has been experimentally validated by means of tension and compression tests and the results have been correlated with the pre and post-deformation microstructures. © 2017 Elsevier B.V.

Sushanta Kumar Panigrahi

Department of Mechanical Engineering

B. N. Sahoo

Compression testing

Magnesium

Mechanical properties

Precipitates

TITANIUM CARBIDE

COMPRESSION ASYMMETRY

DEFORMATION MICROSTRUCTURE

MAGNESIUM MATRIX COMPOSITE

MG MATRIX COMPOSITES

Microstructural analysis

PEAK AGED CONDITIONS

TENSION COMPRESSIONS

Tension and compression

Magnesium alloys

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Alloys and Compounds

ZE41 Mg–TiB2 metal matrix composites with improved mechanical properties were synthesized via a novel processing route. In this process, the Ti–B system was developed without addition of third intermediate metallic Al powder, thereby preventing formation of any undesirable hazardous by-products from salt system (Al–K2TiF6–KBF4) and brittle TiAl3 intermetallic phase from master alloy (Al–Ti–B). Sub-micron sized TiB2 particles (5, 10 and 15 wt%) were reinforced in the ZE41-Mg alloy and the influence of TiB2 particles and its weight fraction on mechanical properties of composite materials were studied in details with an emphasis on microstructural characterization. The microstructural characterization shows reasonable uniform distribution of TiB2 particles in lower weight fraction of reinforcement and strong interfacial bonding with the matrix. A significant enhancement of the strength as well as grain refinement of composite were observed with increased TiB2 particles. The effect of TiB2 particle content on Young's modulus and yield strength was correlated via theoretical/mathematical modeling and experimental investigations. The strengthening mechanisms for strength enhancement of composites were established. © 2019 Elsevier B.V.

Materials Science and Engineering A

Effect of in-situ sub-micron sized TiB2 reinforcement on microstructure and mechanical properties in ZE41 magnesium matrix composites

In the present work, dry sliding wear behavior of AZ91 Magnesium alloy with different microstructural conditions are investigated under a set of processing parameters. The investigations are carried out on four material conditions: (i) AZ91 Magnesium alloy, (ii) AZ91 alloy with precipitate, (iii) AZ91 alloy with in-situ TiC + TiB2 reinforcement and (iv) AZ91 alloy with both precipitate and in-situ reinforcement. The effect of microstructural modification on different wear mechanisms namely: abrasive, oxidation, delamination and melt wear is established. The processing windows for all the four types of wear mechanism are established and the wear mechanism maps are also constructed by correlating the microstructures of worn surfaces and test parameters. The inherent mechanisms of all the four types of wear behavior are established for all the material conditions. © 2019 Elsevier Ltd

Tribology International

Development of wear maps of in-situ TiC+TiB2 reinforced AZ91 Mg matrix composite with varying microstructural conditions

Magnesium matrix in-situ composites with hybrid TiC+TiB2 reinforcement are potential materials for automobile and aerospace applications. It is essential to establish the processing map of such composites as these materials may undergo several thermo-mechanical processes while manufacturing engineering components. In the current work, AZ91 Magnesium matrix TiC+TiB2 reinforces hybrid in-situ along with its base counterpart were developed and subjected to solutionization followed by peak aging treatment. The safe processing zone for both base and in-situ composite at all heat treatment conditions have been established through processing map based on dynamic materials model (DMM) by conducting hot compression tests at various temperatures (250 °C – 450 °C) and strain rates (0.001 s−1 – 10 s−1). Two regions: stable and instable were identified from processing map for all the material conditions. Dynamic recrystallization is the main dominant mechanism in stable region, whereas instable region is characterized by twin and intergranular cracks. To understand the mechanism of hot deformation behavior, activation energy is calculated based on constitutive model for all material conditions. The developed in-situ composite in peak aged condition is found to possess higher activation energy (∼230 kJ/mol) as compared to base alloy (∼126 kJ/mol). A correlation between constitutive model and processing map have been established with an emphasis on their microstructures. © 2018 Elsevier B.V.

Deformation behavior and processing map development of AZ91 Mg alloy with and without addition of hybrid in-situ TiC+TiB2 reinforcement

The bulk ultrafine grained (UFG) AA6063/4 wt.%SiC composite sheets with varying reinforcement size of SiC (12 μm (coarse), 1 μm (fine) and 45 nm (nano)) have been developed with a novel hybrid process of stir casting and cryo-severe plastic deformation process (cryorolling). The influence of SiC particle size during development of UFG composites and its effect on microstructural modification, strengthening mechanism and failure mechanism was studied in detail. The resultant effect of cryorolling and size of SiC particles has resulted in significant microstructural refinement (less than 350 nm in all UFG composites) and accumulation of high dislocation density; which resulted in improvement in tensile strength as 88%, 108% and 141% in UFG composites reinforced with coarse, fine and nano particles respectively as compared to the unreinforced base alloy. A good agreement in theoretical and experiment yield strength of UFG coarse and fine composites is observed with a variation in UFG nano composite. © 2018 Elsevier B.V.

Development and strengthening mechanisms of bulk ultrafine grained AA6063/SiC composite sheets with varying reinforcement size ranging from nano to micro domain

In the present work, a hybrid manufacturing route, combining stir casting with cryorolling, is proposed for production of Ultrafine grained (UFG) nano composite sheets using an Al 1050 matrix in combination with β-SiC particles (0.5 wt%, 1 wt%, 2 wt%). The method provides the scope for generating UFG microstructures with homogeneous distributions of nano particles that are difficult to achieve with existing manufacturing routes. The influence of the nano SiC reinforcement on the mechanical properties of the UFG nano composites were studied with an emphasis on the characterization of the microstructure. The results show that with an increasing content of reinforcement, the degree of grain refinement and strength of the UFG nano composite increases while the ductility reduces. The microstructural information and the obtained yield strengths of the UFG nano composites were validated with a mathematical model. For this, an existing dislocation density based model was modified to account for the effect of nano reinforcement and processing parameters. © 2018

Development of bulk ultrafine grained Al-SiC nano composite sheets by a SPD based hybrid process: Experimental and theoretical studies

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-TiB2 reinforced magnesium matrix composites. The reinforcement is formed in-situ from elemental Ti and B4C powders and molten Mg-Al-Zn alloy without any addition of a third phase metal powder such as aluminum. Results show that the distribution of TiC and TiB2 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-Mg17Al12 phase into α-Mg matrix 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 analyzing the fractographs and microstructures of the material. © 2016 Elsevier Ltd

Materials and Design

Synthesis, characterization and mechanical properties of in-situ (TiC-TiB2) reinforced magnesium matrix composite

Frontiers in Materials

Nanoindentation Characterization on Microhardness of Micron-Level TiC and TiB Reinforcements in in-situ Synthesized (TiC+TiB)/Ti-6Al-4V Composite

Composites Part B: Engineering

Mechanical behavior of AZ31/Al 2 O 3 magnesium alloy nanocomposites prepared using ultrasound assisted stir casting

The role of Al content on deformation behavior and related texture evolution during hot rolling of Mg-Al-Zn alloys

Enhancing strength and ductility of Mg-Zn-Gd alloy via slow-speed extrusion combined with pre-forging

A study on the combined effect of in-situ (TiC-TiB2) reinforcement and aging treatment on the yield asymmetry of magnesium matrix composite

Journal	Data powered by TypesetJournal of Alloys and Compounds
Publisher	Data powered by TypesetElsevier Ltd
ISSN	09258388
Open Access	No