International Journal of Computational Materials Science and Surface Engineering (7 papers in press)
Power Voronoi assisted modeling and simulation of austenite formation during continuous heating in C35 steel
by SANCHU S, Biju N, V. N. Narayanan Namboothiri, Minu K K
Abstract: In the development of materials with desired properties, modeling of transformation kinetics is an important aspect. Ability of power Voronoi assisted simulation in predicting transformation kinetics is examined in this work. Initially, a mathematical model is derived incorporating the geometrical properties of power Voronoi diagram and classical nucleation theory. This is the governing equation for the power Voronoi assisted simulation. Transformed fractions at different temperatures are calculated using this equation. Simulation of microstructure evolution is carried out using power Voronoi diagram by giving nucleation rate and interface velocity as input. From the resultant geometry, it is possible to calculate the transformed fraction. The results are validated and verified using the available experimental results in literature. On comparison, it is evident that, transformed fraction can be predicted with less than 4% error using power voronoi assisted simulation model with the derived governing equation. Thus, Power Voronoi diagram can be used to simulate microstructure evolution during austenitisation with reasonably good accuracy in phase fraction.
Keywords: Austenite formation; Power Voronoi diagram; modeling of phase transformation kinetics.
One-pot Synthesis Method of Copper Nanoparticles in Air
by Yingqiong Yong, Yanfei Liu, Jun Wang, Shengju Song, Hongjiang Zhang
Abstract: A feasible one-pot synthesis method for the preparation of copper nanoparticles under ambient atmosphere is put forward. Copper oxide and D-isoascorbic acid were chosen as the copper precursor and mild reducing agent, respectively. Oleylamine and octylamine were selected as the capping agents. The effects of the amount and alkyl chain length of capping agent on the synthesis of copper nanoparticles were studied. Antioxidized copper nanoparticles were prepared successfully without the protection of inert atmosphere. The minimum average size of obtained copper nanoparticles was 149
Keywords: nanoparticles; copper; one-step process.
Parametric Optimization of High Speed Turning Operation of Hybrid Aluminium Composites Using Taguchi Based Grey Relational Analysis
by A. Thirumoorthy, T.V. Arjunan, M. Arulraj, R. Kumaravelan, T.C.R. Dinesh
Abstract: In the field of Metal Matrix Composites (MMCs), most of researches are being carried out with carbide, alumina and boride as reinforcement. Nitrides and Oxides are also suitable candidates to be used as reinforcement. There is a huge scope to study the effect of nitride and oxide on the mechanical and machining behavior of composite materials. Therefore this paper has set the primary objective of developing the hybrid aluminium based composite and studying the hardness and machining behaviour of high hardness hybrid composite of MMCs by reinforcing with nitride and oxide. The composition chosen are the first sample composition with 6% of Silicon Nitride (Si3N4) and 3% of Magnesium Oxide and another with 3% Si3N4 and 3% MgO. Al6061 matrix with blended Magnesium Oxide and Silicon Nitride is produced using stir casting process. Computer Numerical Control (CNC) turning operation has been carried out on the composite developed. The main responses considered in this study are Surface Roughness (SR) and Material Removal Rate (MRR) and machining parameters such as feed rate, depth of cut and cutting speed, are chosen. Among these, feed and depth of cut are most influencing factor for the machining of hybrid composites.
Keywords: Hybrid Composite; Silicon Nitride; High-Speed Turning; Grey Relational Analysis.
Microstructure and mechanical properties of nano-WC decorated AlSi10Mg composite produced by selective laser melting: Effect of heat treatment
by Han Ye, Fangbin Le, Jianqiang Zhang, Yong Liu
Abstract: Nano-WC and AlSi10Mg composite powder were fabricated by gas-atomized for selective laser melting (SLM). Here, the influence of the heat treatment conditions on microstructure and mechanical properties of WC/AlSi10Mg produced by SLM were investigated, and the mechanisms of microstructure evolution were elucidated. The cellular microstructure in the as-deposited sample can be divided into three regions: coarse cellular zone(CCZ), heat affected zone (HAZ) and fine cellular zone(FCZ), which corresponding eutectic Si density are 28
Keywords: Additive Manufacturing; AlSi10Mg alloy; WC; Mechanism analysis;.
Effect of heat treatment on the microstructures and hardness of selective laser melted Rene88DT superalloy
by Jian Liu
Abstract: Selective laser melted Rene88DT specimens with columnar grains (specimen C) and near-equiaxed grains (specimen E) were fabricated, on which solution-aging and direct aging treatments were applied respectively. The evolution of microstructures and hardness of both specimens was investigated. Results show that specimen C showed columnar grains with aspect ratio of 3.6 and 5% difference in hardness between vertical and horizontal directions, while specimen E with near-equiaxed grains (aspect ratio of 1-2) was isotropic. The as-deposited alloys consisted of ?-matrix, carbides and Laves phases. After solution-aging treatment, equiaxed grains (56 ?m) with annealing twins, blocky ? phases (1 ?m) and dispersively distributed ?' (40 nm) were observed in specimen C. After direct aging treatment, rod-like ?' phases with 40 nm in length and 15 nm in diameter were precipitated in specimen E. Specimen E showed higher hardness than specimen C because of stronger grain boundary strengthening, substructure strengthening and second-phase strengthening.
Keywords: selective laser melting; Rene88DT superalloy; heat treatment; microstructures; hardness.
Numerical Simulation and Experimental Study on Non-uniform Strain during Hot Compression of Aluminum Alloy
by Haigen Jian, Yedong Wang, Xiaomei Yang, Chengji Mi, Xinlei Lei, Wei Zhang
Abstract: The finite element numerical simulation of hot compression deformation process of B93 aluminum alloy was carried out by DEFORM-3D software. Besides, the microstructure characteristics of deformed specimens in different regions and the relationship between non-uniform strain and dynamic recrystallization during deformation were analyzed by experimental study. The results show that the hot compression process of B93 aluminum alloy obviously exhibits a nonuniform characteristic of deformation, the region with the largest equivalent strain is the most prone to deformation. Also, in the largest equivalent strain zone, dynamic recrystallization reacts the most complete, and the grain size reaches the minimum value. Nonuniform deformation show a rising tendency with the increase of strain rate and deformation temperature, and the influence of strain rate on nonuniform deformation is slightly greater than that of deformation temperature. The most suitable hot working process for the alloy is 410~430?/0.001~0.01s-1.
Keywords: B93 aluminum; Hot deformation; Finite element analysis; Effective plastic strain.
Special Issue on: Advanced Materials and Manufacturing Technology in Transportation Engineering
Prediction on the operation performance of axial piston pump at low suction pressure
by Miaomiao Wang, Zhimin Guo, Junjie Zhou, Guangming Sun, Wenpan Gao
Abstract: The operation performance of the axial piston pump is affected by external environment pressure, and its conditions at low suction pressure are less studied. The oil model and fluid dynamic model of the axial piston pump are developed and a novel approach for predicting the operation performance of such machines at low suction pressure based on this model is presented. It was found that the inlet pressure of the suction chamber changes linearly with the environment pressure. Compared to the present data from the product manual, this approach is proved to be valid and is used to predict the maximum operating speed and suction pressure at other environment pressure, therefore the low-pressure operating performance map is enriched for the referring of more users of the pump. In future, this study provides a new method for the prediction and the design guide of pump operation at low suction pressures.
Keywords: axial piston pump; low suction pressure; operation performance; maximum operating speed; compressible liquid.