Heat Treatment of Molten Rapidly Quenched Precursor as a Method to Improve the Glass Forming Ability of Alloys

Abstract

Improvement of glass forming ability (GFA) of two soft magnetic amorphous alloys (Fe75.5Ni1 3Si8.6B13.5 and Co69.6Fe1.3Mn4.5Si14.3B9 3Mo1) by heat treatment of melts prepared from different precursors (bulk ingot, rapidly quenched ribbons and granules) was studied. An assumption that the maximum undercooling ability corresponds to the maximum GFA was used to optimize the heat treatment mode. A temperature range was found by DTA for each alloy melt, favoring its undercooling (so called “undercoolable melt”). Usage of rapidly quenched precursor expands the range towards lower temperatures. GFA of the alloys was estimated by several melt quench techniques (casting, spinning and INROWASP). Fully amorphous samples with the thickness of 0.06–0.5 mm were prepared.

On the solidification of the Fe50Cr15Mo14C15B6 bulk-amorphized alloy

“…The melt temperature area which is characterized by the greatest values of supercooling has been found experimentally [11,12]. The quenching of the melt from this temperature area results in an increase of the glass forming ability [11,12] as well as the shape change of the structure and properties of the alloys obtained [13]. At the same time, as shown in [10,14], in the polytherms of the structural-sensitive properties of melts (viscosity, density, etc.)…”

“…This is due to the dependence of the structure formation processes on the structural state of the liquid phase which is inherited to some extent in the solidification process [10]. The melt temperature area which is characterized by the greatest values of supercooling has been found experimentally [11,12]. The quenching of the melt from this temperature area results in an increase of the glass forming ability [11,12] as well as the shape change of the structure and properties of the alloys obtained [13].…”

Effect of Co substitution for Ni on the microstructure and magnetic properties of (Fe, Ni)-based amorphous alloys produced by melt spinning

“…Therefore, since their discovery, their properties have been extensively studied due to a great deal of interest for fundamental reasons and their enormous potential in practical applications [1][2][3]. Particularly, the glassy alloys can be produced over a fairly wide range of compositions [4,5].…”

Influence of precursor on magnetostatic and dynamic properties of Co68Fe4 Cr4Si12B12 amorphous ribbons

“…It was shown [1] that the improvement of GFA of amorphous alloys can be achieved by a rational choice of a precursor and its heat treatment. The main requirement to the precursor is absence of rough precipitation of primary phases, which need a high overheating of melting to be dissolved completely.…”