Phase Transformation of High Velocity Air Fuel (HVAF)-Sprayed Al-Cu-Fe-Si Quasicrystalline Coating

Mingwei Cai,Jun Shen

doi:10.3390/met10060834

Abstract

Al-Cu-Fe-Si quasicrystalline coatings were prepared by high velocity air fuel spraying to study their phase transformation during the process. The feedstock powder and coating were phase characterized by scanning electron microscopy, X-ray diffractometry, differential scanning calorimetry, and transmission electron microscopy. Results show that Al3Cu2 phase, a small amount of λ-Al13Fe4 phase, quasicrystalline phase (QC), amorphous phase, and β-Al (Cu, Fe, Si) phase were present in the sprayed Al50Cu20Fe15Si15 powder. For a typical flattened powder particle, the splat periphery was surrounded by a 1 µm thick amorphous phase. The inside area of the splat was composed of the QC covered by the Al3Cu2 and Si-rich β-Al (Cu, Fe, Si) phases. Another kind of Cu- rich β-Al (Cu, Fe, Si) phase can be found close to the amorphous area with a similar composition to the original β-Al (Cu, Fe, Si) phase in the powder. Different phases were observed when the periphery and inside area of the splat were compared. This result was caused by the difference in the heating and cooling rates.

Highlights

A solid state between crystalline and non-crystalline solids, which was later identified as a quasicrystal, was first reported in a rapidly solidified Al-Mn alloy [1]
Al-Cu-Fe-Si coatings containing quasicrystalline phase (QC) and amorphous phases were prepared on an aluminum alloy with a thickness of approximately 240 μm
The feedstock powder was composed of the Al3 Cu2 phase whose prototype is Ni2 Al3, CsCl type β-Al (Cu, Fe, Si), λ-Al13 Fe4, QC and amorphous phases

Summary

Introduction

A solid state between crystalline and non-crystalline solids, which was later identified as a quasicrystal, was first reported in a rapidly solidified Al-Mn alloy [1]. In terms of atomic structure, quasicrystals have a long-range atomic arrangement similar to crystals but exhibit fivefold axis symmetries, which cannot exist in classical crystallography This class of material exhibits excellent properties, such as low surface energy [2,3], low electrical and thermal conductivity [4,5], remarkable optical properties [6], good wear resistance [7], high resistance to oxidation [8], and corrosion [9]. Despite their excellent performance, the applications of quasicrystal alloys as structural materials are limited by their intrinsic high brittleness and poor deformability at room temperature. Ribbon, film, and powder can be obtained with different spatial scales, suggesting distinct solidification rates

Methods

Results

Conclusion