Bulk metallic glass (BMG) alloys exhibit excellent nature in mechanical, chemical and magnetic properties. Because random atomic arrangement is stable in liquid state, glass phase of BMG alloys can be obtained easily from liquid even at much lower quenching rate, like 0.1–100K/s. That is, they don't need to be cooled down at more than 106K/s from liquid state, such as an ordinal amorphous alloy. Thus, thick metallic glass coatings have been successfully fabricated on the substrate by regular thermal spraying methods. However, glass forming mechanism in thermal spray process hasn't been understood clearly up to today.
In this study, in order to elucidate the formation mechanism of glass phase in iron-base metallic glass, in-flight temperature history of the particles was estimated by comparing the results between Fe43Cr16Mo16C15B10 metallic glass powder and its crystallized powder by pre-heat treatment. Moreover, comparison of the particles behavior between atmospheric plasma spraying (APS), which is characterized as high temperature low velocity process, and high velocity oxy fuel spraying (HVOF), which characterized as low temperature high velocity process, was conducted.
Consequently, it was revealed that the thick coating with glass phase of BMG can be easily obtained in HVOF process by depositing the particles at super-cooled liquid state without heating to the liquid phase during spraying.
