Nondestructive Methodology for Identification of Local Discontinuities in Aluminide Layer-Coated MAR 247 during Its Fatigue Performance

Abstract

In this paper, the fatigue performance of the aluminide layer-coated and as-received MAR 247 nickel superalloy with three different initial microstructures (fine grain, coarse grain and column-structured grain) was monitored using nondestructive, eddy current methods. The aluminide layers of 20 and 40 µm were obtained through the chemical vapor deposition (CVD) process in the hydrogen protective atmosphere for 8 and 12 h at the temperature of 1040 °C and internal pressure of 150 mbar. A microstructure of MAR 247 nickel superalloy and the coating were characterized using light optical microscopy (LOM), scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). It was found that fatigue performance was mainly driven by the initial microstructure of MAR 247 nickel superalloy and the thickness of the aluminide layer. Furthermore, the elaborated methodology allowed in situ eddy current measurements that enabled us to localize the area with potential crack initiation and its propagation during 60,000 loading cycles.

Study on High Temperature Properties of Yttrium-Modified Aluminide Coating on K444 Alloy by Chemical Vapor Deposition

“…One effective way to solve these problems is to prepare aluminide coating on the surface of gas turbine blade cavity passage [8,9]. The chemical vapor deposition (CVD) method can realize the internal aluminizing of complex parts by gas reaction, and the infiltrating agent does not have direct contact with the substrate, which has little influence on the workpiece [10,11]. The CVD method can control the coating element content and coating thickness by controlling the reaction gas flow and deposition time, which makes it easy to control the reaction process, thus it has been widely used in the preparation of aluminide coatings in recent years [12].…”

Synthesis, Properties and Applications of Intermetallics, Ceramic and Cermet Coatings

“…This Special Issue is focused on various conventional synthesis methods of different intermetallic, ceramic, and composite coatings obtained by thermal (D-gun and Arc) spraying [ 6 , 7 ], the CVD process [ 8 , 9 , 10 ], magnetron sputtering [ 11 ], anodization [ 12 ], and during the sintering of aluminum, iron and particulate mullite ceramic powders using self-propagated high-temperature synthesis (SHS) [ 13 ].…”

“…Since the extreme performance conditions of modern aircraft engine turbines require the use of heat-resistant materials, MAR 247 nickel-based alloy is also in the scope of the analyzed materials [ 8 , 9 ]. The maximum operating temperature of contemporary nickel superalloys is 1100 °C, which is why it is necessary to use protective coatings on the hot parts of the aircraft engine turbines [ 15 ].…”

“…With the increasing demands of the aircraft industry, the increasing application of non-destructive testing to determine the process-dependent properties of the material and to further reduce the amount of experimental work and minimize the manufacturing costs are observed. This is also accompanied by ever-increasing demands for the scientific description of applied measurement methodologies, such as, e.g., “Nondestructive Methodology for identification of local discontinuities in aluminide layer-coated MAR 247 during Its fatigue performance” [ 9 ].…”

“…It was found that the elaborated methodology is an effective tool to monitor the degradation of the material. Furthermore, the applied assessment enabled us to localize the area with potential crack initiation and its propagation during 60,000 loading cycles [ 9 ]. This was mainly influenced by the initial microstructure of MAR 247 nickel superalloy and the thickness of the aluminide layer synthesized in the CVD process.…”