Effects of Rare Earth Elements on Properties of Ni-Base Superalloy Powders and Coatings

Chunlian Hu,Shanglin Hou

doi:10.3390/coatings7020030

Chunlian Hu, Shanglin Hou

Open Access

https://doi.org/10.3390/coatings7020030

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Journal: Coatings	Publication Date: Feb 16, 2017
Citations: 9	License type: CC BY 4.0

Affiliation: Lanzhou University of Technology

Abstract

NiCrMoY alloy powders were prepared using inert gas atomization by incorporation of rare earth elements, such as Mo, Nb, and Y into Ni60A powders, the coatings were sprayed by oxy-acetylene flame spray and then remelted with high-frequency induction. The morphologies, hollow particle ratio, particle-size distribution, apparent density, flowability, and the oxygen content of the NiCrMoY alloy powders were investigated, and the microstructure and hardness of the coatings were evaluated by optical microscopy (OM). Due to incorporation of the rare earth elements of Mo, Nb, or Y, the majority of the NiCrMoY alloy particles are near-spherical, the minority of which have small satellites, the surface of the particles is smoother and hollow particles are fewer, the particles exhibit larger apparent density and lower flowability than those of particles without incorporation, i.e., Ni60A powders, and particle-size distribution exhibits a single peak and fits normal distribution. The microstructure of the NiCrMoY alloy coatings exhibits finer structure and Rockwell hardness HRC of 60–63 in which the bulk- and needle-like hard phases are formed.

Highlights

Due to excellent weldability properties, surface stability, corrosion resistance, and mechanical properties at high temperature, nickel-based superalloys are widely used for gasturbine components and other applications, such as the base materials for hot components, e.g., hot parts of aerospace turbine engines [1]
NiCrMoY alloy powders were prepared by using inert gas atomization with incorporation of rare earth elements, such as Mo, Nb, and Y into Ni60A powders, the coatings were sprayed by oxy-acetylene flame spray and remelted with high-frequency induction
The chemical compositions of the Ni60A alloy and NiCrMoY alloy powders are shown in Table 1 which was measured at the Testing Center of the Shanghai Research Institute of Materials according to ASTM E1019-11 [18], ASTM E2594-09(2014) [19], ASTM E354-14 [20], and ISO4938:1988 [21]

Summary

Introduction

Due to excellent weldability properties, surface stability, corrosion resistance, and mechanical properties at high temperature, nickel-based superalloys are widely used for gasturbine components and other applications, such as the base materials for hot components, e.g., hot parts of aerospace turbine engines [1]. Nickel-based coatings can function either as overlay coatings or asbond coats in a thermal barrier coating system. They are usually applied using thermal spraying processes, such as low-pressure plasma spraying (LPPS), high velocity oxygen fuel spraying (HVOF), vacuum plasmas praying (VPS) and atmospheric plasma spraying (APS) [2]. Incorporation of rare earth (RE) elements into alloys may improve their high-temperature oxidation resistance or other mechanical properties. Incorporation of minor amounts of rare earth elements, such as Ce, Y, Zr, La, or their oxides enhance the bonding strength of the oxide layer [4] and improve the high-temperature oxidation resistance of alumina- and chromia-forming alloys [5].

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