Manufacturing of Functionally Graded Materials

2000 ◽  
Author(s):  
Franz-Josef Kahlen ◽  
Aravinda Kar
Keyword(s):  
Functionally Graded ◽  
Graded Materials ◽  
Nickel Based Superalloy ◽  
Melt Pool ◽  
Plume Temperature ◽  
One Step ◽  
Solid Liquid ◽  
Melt Pool Characteristics ◽  
Deposition Height ◽  
Metal Layers

Abstract Laser deposition of metal layers has been recognized in recent years as a one-step process to fabricate metal parts. A one-dimensional model was developed to calculate the plume temperature, process parameters and melt pool characteristics. The model accounts for the transmission of the laser beam through the plume, energy transfer in the molten phase and the Stefan conditions at the solid-liquid and liquid-vapor interfaces. The surface temperature at the molten surface is found to exceed the normal boiling temperature causing the pressure to be higher than one atmospheric pressure. The plume temperatures were found to be below the respective material’s ionization temperature. The calculated plume temperatures are in good agreement with the values obtained from the spectral data. Also, the model predictions for remelt layer depth, deposition height and plasma height compare well with experimental data. The authors have employed this one-step technique to create graded materials by varying the part’s composition from 100% stainless steel to a 100% nickel-based superalloy. Mechanical properties of these graded materials are measured and the effects of slow solidification rates are investigated.

Thermal and Dimensional Process Characteristics in Laser-Aided Rapid Manufacturing

2000 ◽  
Author(s):  
Franz-Josef Kahlen ◽  
Aravinda Kar
Keyword(s):  
Laser Beam ◽  
Three Dimensional ◽  
Emission Spectra ◽  
Phase Changes ◽  
Process Characteristics ◽  
Melt Pool ◽  
Plume Temperature ◽  
Solid Liquid ◽  
Melt Pool Characteristics ◽  
Deposition Height

Abstract Three-dimensional cylindrical and wall-like structures of copper, Ti-6Al-4V, aluminum, and stainless steel 304 were fabricated by melting the powders of these materials with a CO2 laser beam. A vapor-plasma plume is generated at the top of the melt layer. The emission spectra of the plume were recorded using an optical multichannel analyzer, and the plume temperatures are determined to be in the range of 4920 K to 6720 K. A one-dimensional model is developed to calculate the plume temperature, deposition geometry and melt pool characteristics. The model accounts for the transmission of the laser beam through the plume, energy transfer in the molten phase and the phase changes at the solid-liquid and liquid-vapor interfaces. The surface temperature at the molten surface is found to exceed the normal boiling temperature causing the pressure to be higher than one atmospheric pressure. The calculated plume temperatures are in good agreement with the values obtained from the spectral data. Also, the model predictions for remelt layer depth, deposition height and plasma height compare well with experimental data.

Functionally Graded Materials produced with High Power Lasers

2001 ◽  
Vol 697 ◽  
Author(s):  
Jeff Th. De Hosson ◽  
Yutao Pei
Keyword(s):  
Functionally Graded Materials ◽  
Composite Layer ◽  
Decomposition Reaction ◽  
Functionally Graded ◽  
Orientation Relationships ◽  
Mechanism Of Formation ◽  
Graded Materials ◽  
Melt Pool ◽  
Injection Model ◽  
First Time

AbstractWith a well-controlled laser melt injection (LMI) process, for the first time the feasibility is demonstrated to produce SiC particles (SiCp) reinforced Ti6Al4V functionally graded materials (FGMs). SiCp are injected just behind the laser beam into the extended part of the laser melt pool that is formed at relatively high beam scanning velocities. The process allows for the minimization of the decomposition reaction between SiCp and Ti6Al4V melt, and also leads to FGMs of SiCp/Ti6Al4V instead of a homogeneous composite layer on Ti6Al4V substrates. An injection model is designed based on the temperature/viscosity field of the laser pool for a deeper understanding the mechanism of formation of the FGMs with LMI. The model is based on finite element calculations of the temperature field in the melt pool, physical considerations of the LMI process and it is supported by experimental observations. Three types of reaction layers are observed around SiCp, namely a thin monocrystalline TiC layer, a cellular polycrystalline TiC layer and a thick mixed layer of TiC with Ti5Si3. Among them, only the monocrystalline TiC layer exhibits particular orientation relationships to the SiCp lattice, i.e. (111)TiC//(0001)SiC and <110>TiC//<1100>SiC or (111)TiC // (1012)SiC and <110>TiC//<1210>SiC. These two kinds of TiC reaction layers act as a barrier against the interfacial reaction and its swift formation during rapid cooling hinders the dissolution of SiCp in the Ti-melt.

scholarly journals On the Feasibility of Tailoring Copper–Nickel Functionally Graded Materials Fabricated through Laser Metal Deposition

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 287 ◽  
Author(s):  
Sreekar Karnati ◽  
Yunlu Zhang ◽  
Frank F. Liou ◽  
Joseph W. Newkirk
Keyword(s):  
Pulse Width Modulation ◽  
Weight Ratio ◽  
Functionally Graded ◽  
Image Correlation ◽  
Material Interface ◽  
Graded Materials ◽  
Copper Nickel ◽  
Duty Cycles ◽  
Graded Material ◽  
Deposition Height

In this study, pulse-width modulation of laser power was identified as a feasible means for varying the chemical gradient in copper–nickel-graded materials. Graded material deposits of 70 wt. %. copper-30 wt. %. nickel on 100 wt. %. nickel and vice versa were deposited and characterized. The 70/30 copper–nickel weight ratio in the feedstock powder was achieved through blending elemental copper and 96 wt. %. Ni–Delero-22 alloy. At the dissimilar material interface over the course of four layers, the duty cycle of power was ramped down from a high value to optimized deposition conditions. This change was theorized to influence the remelting and deposition height, and by extension, vary the chemistry gradient. X-ray Energy Dispersive Spectroscopy (EDS) analysis showed significant differences in the span and nature of chemistry gradient with varying duty cycles. These observations were also supported by the variation in microhardness values across the interface. The influence of different chemistry gradients on the tensile performance was observed through mini-tensile testing, coupled with Digital Image Correlation (DIC). The strain fields from the DIC analysis showed variations in strain for different chemistry gradients. The strength measurements from these specimens were also different for different chemistry gradients. The site of failure was observed to always occur within the copper-rich region.

Dynamic Analysis with Stress Recovery for Functionally Graded Materials: Numerical Simulation and Experimental Benchmarking

2014 ◽  
Vol 2 (1) ◽  
pp. 21
Author(s):  
Carlos Alberto Dutra Fraga Filho ◽  
Fernando César Meira Menandro ◽  
Rivânia Hermógenes Paulino de Romero ◽  
Juan Sérgio Romero Saenz
Keyword(s):  
Numerical Simulation ◽  
Dynamic Analysis ◽  
Functionally Graded Materials ◽  
Functionally Graded ◽  
Stress Recovery ◽  
Graded Materials

A Study on the Rearrangement of Dialkyl 1-Aryl-1-hydroxymethylphosphonates to Benzyl Phosphates

2020 ◽  
Vol 24 (4) ◽  
pp. 465-471 ◽  
Author(s):  
Zita Rádai ◽  
Réka Szabó ◽  
Áron Szigetvári ◽  
Nóra Zsuzsa Kiss ◽  
Zoltán Mucsi ◽  
...  
Keyword(s):  
Quantum Chemical ◽  
Room Temperature ◽  
Phase Transfer ◽  
One Pot ◽  
Substrate Dependence ◽  
Triethylbenzylammonium Chloride ◽  
One Step ◽  
The Pudovik Reaction ◽  
The One ◽  
Solid Liquid

The phospha-Brook rearrangement of dialkyl 1-aryl-1-hydroxymethylphosphonates (HPs) to the corresponding benzyl phosphates (BPs) has been elaborated under solid-liquid phase transfer catalytic conditions. The best procedure involved the use of triethylbenzylammonium chloride as the catalyst and Cs2CO3 as the base in acetonitrile as the solvent at room temperature. The substrate dependence of the rearrangement has been studied, and the mechanism of the transformation under discussion was explored by quantum chemical calculations. The key intermediate is an oxaphosphirane. The one-pot version starting with the Pudovik reaction has also been developed. The conditions of this tandem transformation were the same, as those for the one-step HP→BP conversion.

Sign in / Sign up

Export Citation Format

Share Document