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Detroit, MI, United States

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.


Bhattacharya S.,University of Michigan | Bhattacharya S.,Carnegie Mellon University | Dinda G.P.,Center for Advanced Technologies | Dinda G.P.,Wayne State University | And 2 more authors.
Journal of Materials Science | Year: 2014

Cu-38Ni alloy was deposited on C71500 (Cu-30Ni) substrates by a laser-aided direct metal deposition technique using CO2 and diode lasers. Structure-property relationships of deposited specimens were investigated by optical microscopy, electron microscopy, X-ray diffraction techniques, and microhardness and tensile measurements. Laser-deposited specimens' microstructures were primarily dendritic, forming columnar grains growing epitaxially from the substrate and subsequent layers along the preferred crystallographic growth. The grain growth pattern and grain size distribution was significantly different in both specimens. The lattice parameter of the solid solution phase was relatively larger in diode laser-formed specimen; CO2 laser-formed specimens showed relatively higher but non-uniform hardness distribution whereas a very uniform hardness distribution was observed in diode laser formed specimens. Diode laser formed specimens showed higher tensile properties compared to CO2 laser formed specimens which were comparable to C71500 substrates. Microstructure and mechanical behavior were explained based on laser processing parameters. © 2013 Springer Science+Business Media New York.


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.

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