Showing papers by "Bhagwati Prasad Kashyap published in 2012"
TL;DR: In this article, the formation and growth of intermetallic compounds by diffusion reaction of Cu and Ti were investigated in the temperature range 720-860°C using bulk diffusion couples.
Abstract: The formation and growth of intermetallic compounds by diffusion reaction of Cu and Ti were investigated in the temperature range 720–860°C using bulk diffusion couples. Only four, out of the seven stable intermediate compounds of the Cu–Ti system, were formed in the diffusion reaction zone in the sequence CuTi, Cu4Ti, Cu4Ti3 and CuTi2. The activation energies required for the growth of these compounds were determined. The diffusion characteristics of Cu4Ti, CuTi and Cu4Ti3 and Cu(Ti) solid solution were evaluated. The activation energies for diffusion in these compounds were 192.2, 187.7 and 209.2 kJ mol−1 respectively, while in Cu(Ti), the activation energy increased linearly from 201.0 kJ mol−1 to 247.5 kJ mol−1 with increasing concentration of Ti, in the range 0.5–4.0 at.%. The impurity diffusion coefficient of Ti in Cu and its temperature dependence were also estimated. A correlation between the impurity diffusion parameters for several elements in Cu matrix has been established.
22 citations
TL;DR: In this article, the effects of grain size, test temperature and strain rate on flow stSuperscSuperscript textript textress deformation were analyzed to develop the constitutive relationship for supsuperscript texterplastic deformation.
Abstract: Fine grains were developed in Mg-3Al-1Zn (AZ31) alloy by isothermal caliber rolling at five different temperatures in the range of 250-450°C. The samples of different grain sizes were deformed by constant strain rate and differential strain rate test techniques over the temperature range of 220-450 °C and strain rate range of 10-5 to 10-1 s-1. The effects of grain size, test temperature and strain rate on flow stSuperscSuperscript textript textress were analysed to develop the constitutive relationship for supSuperscript texterplastic deformation. The parameters of the constitutive relationship obtained from the constant strain rate tests and differential strain rate tests were used to find out the material constant A of the constitutive relationship.
7 citations
TL;DR: In this article, the authors brought out the kinetics of dissolution of γ phase and evaluated its effect on mechanical properties using as-cast AZ80 Mg alloy, which contained 70% α-Mg and 30% eutectic phase with increasing homogenization time.
Abstract: As-cast AZ80 Mg alloy contains α-Mg, partially divorce eutectic of α and γ (Mg17Al12), fully divorce eutectic of α and γ, and lamellar eutectic of α and γ phases During homogenization, second phase (γ-Mg17Al12) gets dissolved can change the mechanical properties Therefore, the aim of the present work is to bring out the kinetics of dissolution of γ phase and evaluate its effect on mechanical properties Microstructure evolution during homogenization was investigated as a function of time for 05 to 100 h and at the temperatures of 400° and 439°C In as-cast state, this material was found to contain 70% α-Mg and 30% eutectic phase With increasing homogenization time, dissolution of lamellar eutectic occurs first which is followed by dissolution of fully divorce eutectic and partially divorce eutectic The dissolution kinetics of γ phase was analyzed based on the decrease in its volume fraction as a function of time The time exponent for dissolution was found to be 038 and the activation energy for the dissolution of γ phase was found to be 841 kJ/mol This dissolution of γ phase leads to decrease in hardness and tensile strength with increase in homogenization time
6 citations
TL;DR: The high temperature deformation behavior of near alpha titanium alloy IMI834 with a bimodal microstructure has been evaluated by carrying out isothermal compression tests over a range of temperature and strain rate as discussed by the authors.
Abstract: The high temperature deformation behaviour of near alpha titanium alloy IMI834 with a bimodal microstructure has been evaluated by carrying out isothermal compression tests over a range of temperature and strain rate The optimum thermomechanical processing (TMP) parameters ie, temperature, strain rate that can be used to produce various aeroengine components were identified using dynamic materials modeling (DMM) Using kinetic analysis, a unified constitutive equation that describes the deformation behavior of the material in the selected temperature - strain rate regime has been established and the deformation mechanisms operating in the material were identified
6 citations
TL;DR: In this paper, the Pearlite matrix properties for nanoscale results were analyzed using atomic force microscopy (AFM) in a commercial EN9 steel round product by using micro and nano features of microstructural properties along with micro-cracks and voids.
Abstract: Micro and Nano Features of Microstructural Properties along with Micro-Cracks and Voids, which Severely Affect the Strength and Toughness of the Material, Were Studied in Commercial EN9 Steel Round Product by Using Atomic Force Microscopy (AFM). this Has Overcome the Limitations of Optical and Scanning Microscopy. the Aim of the Present Work Is to Characterize the Pearlite Matrix Properties for Nanoscale Results as Pearlitic Morphology and Lamellae Play a Significant Role in Influencing the Mechanical Properties. it Is Also Shown that the Atomic Force Microscope Is a 3D Characterizing Tool which Can Facilitate Visualizing the Adjacent Corners in Alternate Layers of Ferrite-Cementite Lamellae. it Is Also Noted that the Micro-Sized Cracks Exist at the Weak Interfaces between the Ferrite and Cementite Lamellae, which Would Limit the Work Hardening Property of Pearlite and Thus Reduce the Ultimate Tensile Strength Significantly. in Addition, Phase Transformation from γ-Phase to Pearlite Was Schematically Predicted and Discussed as Evident from Microstructural Characterization.
3 citations
18 May 2012