Center for Advanced Technologies

Detroit, MI, United States

Center for Advanced Technologies

Detroit, MI, United States
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Bhattacharya S.,University of Michigan | Dinda G.P.,Center for Advanced Technologies | Dasgupta A.K.,Center for Advanced Technologies | Natu H.,POM Group, Inc. | And 3 more authors.
Journal of Alloys and Compounds | Year: 2011

In the current investigation Cu-30Ni alloy was successfully laser deposited on a rolled C71500 plate substrate by Direct Metal Deposition technology. The microstructural investigation of the clad was performed using optical and scanning electron microscopy. The phase and crystal structure analysis was performed using X-ray diffraction technique and transmission electron microscopy. The microstructure consisted of columnar and equiaxed dendrites with face centered cubic crystal structure. The dendrites grew epitaxially from the substrate and layer and bead boundaries. Dendrites' growth direction 〈0 0 1〉 and growth angle 60° was maintained in each layer. The average primary dendritic arm spacing at the bottom part of the layers was about 7.5 μm and average secondary dendritic arm spacing in the upper part of the layer varied between 2 μm and 4.5 μm. The lattice parameter of the identified phase was found to be longer than that reported in literature. The reported lattice parameters in literature are however from samples processed under equilibrium conditions. The microhardness of the clad was found to be less than the substrate but very consistent along the clad. Cu-30Ni clad specimen showed higher ultimate tensile strength but lower yield strength and percentage elongation as compared to the C71500 substrate. DMD Cu-30Ni clad/C71500 substrate specimen showed the worst mechanical properties. The corrosion resistance of the specimens was found to decrease in the order DMD Cu-30Ni clad, half-and-half DMD Cu-30Ni clad-C71500 substrate, and C71500 substrate. © 2011 Elsevier B.V. All rights reserved.


Dinda G.P.,Center for Advanced Technologies | Dasgupta A.K.,Center for Advanced Technologies | Bhattacharya S.,University of Michigan | Natu H.,POM Group, Inc. | And 2 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2013

Direct metal deposition (DMD) technology is a laser-aided rapid prototyping method that can be used to fabricate near net shape components from their CAD files. In the present study, a series of Al-Si samples have been deposited by DMD in order to optimize the laser deposition parameters to produce high quality deposit with minimum porosity and maximum deposition rate. This paper presents the microstructural evolution of the as-deposited Al 4047 sample produced with optimized process parameters. Optical, scanning, and transmission electron microscopes have been employed to characterize the microstructure of the deposit. The electron backscattered diffraction method was used to investigate the grain size distribution, grain boundary misorientation, and texture of the deposits. Metallographic investigation revealed that the microstructural morphology strongly varies with the location of the deposit. The layer boundaries consist of equiaxed Si particles distributed in the Al matrix. However, a systematic transition from columnar Al dendrites to equiaxed dendrites has been observed in each layer. The observed variation of the microstructure was correlated with the thermal history and local cooling rate of the melt pool. © 2012 The Minerals, Metals & Materials Society and ASM International.


Paszkiewicz S.,West Pomeranian University of Technology | Pilawka R.,West Pomeranian University of Technology | Dudziec B.,Adam Mickiewicz University | Dudziec B.,Center for Advanced Technologies | And 7 more authors.
European Polymer Journal | Year: 2015

This work is aimed at determining the effect of polyhedral oligomeric silsesquioxanes (POSS) on the microstructure and phase separation of PTT-block-PTMO based nanocomposites, which were prepared by the means of in situ polymerization. Scanning electron microscopy images (along with EDS analysis) confirmed the occurrence of the reaction between the (n-octyl)dimethylsiloxy groups of POSS and functional groups of PTT-block-PTMO copolymer during in situ polymerization, which leads to the formation of excellent dispersed POSS nanoparticles with good interfacial adhesion. The results showed that the addition of POSS affected the crystallization of the PTT rich phase. The DSC results imply that POSS cages in PTT-block-PTMO act as anti-nucleation agents and inhibit the crystallization of PTT hard phase during the cooling down process from the melt shifting crystallization temperature toward lower values. The introduction of POSS does not have great effect on the glass transition temperature of PTMO-rich soft phase, melting temperature of PTT hard phase and degree of crystallinity of the nanocomposites. Moreover, the influence of the presence of nanoparticles on the phase separation of polymer matrix has been observed. © 2015 Elsevier Ltd. All rights reserved.


Dinda G.P.,Center for Advanced Technologies | Dasgupta A.K.,Center for Advanced Technologies | Mazumder J.,University of Michigan
Scripta Materialia | Year: 2012

A nickel-based superalloy was deposited on a nickel-based superalloy substrate by a laser-aided direct metal deposition process. The age-hardening behavior of the as-deposited clad was studied. The effect of laser beam scanning pattern on dendrite growth morphology was investigated using electron backscatter diffraction. Unidirectional laser beam scanning pattern developed a fiber texture; conversely, a backward and forward scanning pattern developed a rotated cube texture in the deposit. This paper reports a route to produce texture-controlled laser clad on a polycrystalline substrate. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Jasthi B.K.,South Dakota School of Mines and Technology | Curtis T.,South Dakota School of Mines and Technology | Widener C.A.,South Dakota School of Mines and Technology | West M.,South Dakota School of Mines and Technology | And 3 more authors.
TMS Annual Meeting | Year: 2015

The main objective of this work is to investigate the effect of friction stir processing on a multi-layered 4340 steel, deposited on a 4340 steel substrate via laser-assisted direct metal deposition (DMD). FSP was performed using W-25%Re-4%HfC and W-25%Re-6%Htr pin tools. X-Ray micro computed tomography (CT) was performed on the as-deposited and processed material to evaluate porosity present in the material. Mechanical properties were also evaluated before and after FSP. FSP effectively eliminated porosity in the as-deposited material and improved the yield and ultimate tensile strengths in the processed region. No significant improvement in the ductility with FSP was observed and the ductility of the processed material is comparable with the as-deposited material. Pin tool wear and microstructural changes associated with FSP were also analyzed and reported.


Bhattacharya S.,University of Michigan | Dinda G.P.,Center for Advanced Technologies | Dasgupta A.K.,Center for Advanced Technologies | Mazumder J.,University of Michigan
Materials Science and Engineering A | Year: 2011

In the current investigation AISI 4340 steel was laser deposited on a rolled mild steel substrate by Direct Metal Deposition (DMD) technology. The microstructural investigation of the clad was performed using optical and electron microscopes and X-ray diffraction techniques. The microstructure consisted of ferrite, martensite and cementite phases. Two types of martensite, lathe-type and plate-type, were observed in the microstructure. Decrease in microhardness values from the top layer to the alloy layer proves that the degree of tempering of the martensite phase increases in the same direction. The lattice parameters of the identified phases were found to be shorter than those reported in literature. The reported parameters in literature are from samples processed under equilibrium conditions. © 2010 Elsevier B.V.


Jasthi B.K.,South Dakota School of Mines and Technology | Klinckman E.,South Dakota School of Mines and Technology | Curtis T.,South Dakota School of Mines and Technology | Widener C.,South Dakota School of Mines and Technology | And 3 more authors.
TMS Annual Meeting | Year: 2013

The main objective of this work is to investigate the effect of post-weld artificial aging (PWAA) on the corrosion resistance and mechanical properties of friction stir welded Al 7475-T73 alloy. Friction stir welding (FSW) was performed on 0.22-in thick plates with varying heat inputs. The PWAA treatment performed was a stabilization treatment at 225° F for 24 hours, followed by aging at 325° F for 4 hours. Electrochemical and alternate immersion corrosion testing was performed to evaluate the effect of PWAA on the corrosion performance. Electrical conductivity measurements along with the tensile properties were evaluated as a function of weld heat input. Both corrosion resistance and mechanical properties of the PWAA specimens were comparable with the parent Al 7475-T73 material.


Dinda G.P.,Center for Advanced Technologies | Dasgupta A.K.,Center for Advanced Technologies | Mazumder J.,University of Michigan
Surface and Coatings Technology | Year: 2012

Laser melting of Al-Si alloys has been investigated extensively, however, little work on the microstructural evolution of laser deposited Al-Si alloys has been reported to date. This paper presents a detailed microstructural investigation of laser deposited Al-11.28Si alloy. Laser aided direct metal deposition (DMD) process has been used to build up solid thin wall samples using Al 4047 prealloyed powder. The evolution of macro- and microstructures of laser deposited Al-Si samples was investigated using X-ray diffraction, optical microscopy, scanning electron microscopy and electron backscattered diffraction techniques. Microstructural observation revealed that the morphology and the length scale of the microstructures are different at different locations of the sample. A periodic transition of microstructural morphology from columnar dendrite to microcellular structure was observed in each layer. The observed difference in the microstructure was correlated with the thermal history of the deposit. © 2011 Elsevier B.V.


Sun G.F.,University of Michigan | Sun G.F.,Jiangsu University | Bhattacharya S.,University of Michigan | Dinda G.P.,Center for Advanced Technologies | And 2 more authors.
Materials Science and Engineering A | Year: 2011

Laser aided direct metal deposition (DMD) has been used to form AISI 4340 steel coating on the AISI 4140 steel substrate. The microstructural property of the DMD coating was analyzed by means of scanning electron microscopy, transmission electron microscopy and X-ray diffractometry. Microhardness of the DMD was measured with a Vickers microhardness tester. Results indicate that DMD can be used to form dense AISI 4340 steel coatings on AISI 4140 steel substrate. The DMD coating is mainly composed of martensite and retained austenite. Consecutive thermal cycles have a remarkable effect on the microstructure of the plan view of the DMD coating and on the corresponding microhardness distribution. Orientation relationships among austenite, martensite and cementite in the DMD coating followed the ones in conventional heat treated steels. As the laser specific energy decreased, cooling rate increased, and martensite peaks broadened and shifted to a lower Bragg's angle. Also martensite lattice parameters increased and austenite lattice parameters decreased due to the above parameter change. © 2011 Elsevier B.V.


Sun G.,University of Michigan | Sun G.,Jiangsu University | Bhattacharya S.,University of Michigan | Dinda G.P.,Center for Advanced Technologies | And 2 more authors.
Scripta Materialia | Year: 2011

Laser-aided direct metal deposition has been used to form an alloy tool steel coating. The microstructure of the deposited material was analyzed by means of scanning electron microscopy and transmission electron microscopy. The formation relationships among martensite, -carbide, cementite and austenite in the coating are discussed. The effect of rapid solidification associated with direct metal deposition on lattice parameters is also reported. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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