Nanocrystalline Formation in Immiscible Cu-Mo System Subjected to Mechanical Alloying

Abstract

The mechanical alloying process has been studied on the Cu-Mo system, the atomic pair of which is characterized by a positive heat of mixing of +19 kJ/mol. The EXAFS and X-ray diffraction measurements have been employed to analyze the structural changes taking place during milling. Two phases mixture of nanocrystalline fcc-Cu and bcc-Mo with a grain size of 10 nm has been formed by MA of Cu30Mo70 powders for 200 hours. The structural analysis based on the EXAFS spectra revealed that bcc and fcc crystal structure clearly do not change around Mo and Cu atoms up to 200 h of milling, respectively. Studies of the thermodynamical considerations by DSC analyses confirmed that the alloying does not occur even after 200 hours of MA in Cu-Mo system.

Defects of ultrathin Cu films on Mo(1 1 0) studied by thermal helium desorption spectrometry

“…A typical helium desorption spectrum (L versus T ) consists of a number of peaks, each peak signifying the desorption of helium from a particular trapping site in the sample. The Cu-Mo system is immiscible and has a positive heat of mixing of +19 kJ mol −1 [21]. Therefore, Cu is not expected to diffuse from the film into the substrate on heating.…”

Mechanically Driven Alloying and Magnetic Properties in Immiscible Mn₈₀Bi₂₀ Nanocrystalline Powders

“…The preparation of metastable phases by mechanical alloying has been investigated extensively in recent years since it has been revealed that this method is a versatile tool for producing materials far from thermodynamic equilibrium. In particular, it has shown that supersaturated solid solution can be obtained in some immiscible systems by heavy mechanical deformation during ball milling [2][3][4][5][6][7][8][9]. Much work has been performed on the magnetism of supersaturated solid solution to this day [10][11][12][13][14][15][16].…”

Formation and Magnetic Properties of Metastable Fe₉₂Bi₈ Nanocrystalline Solid Solution

“…In recent years, there has been long-standing interest in the synthesis of solid solution by mechanical alloying in some traditionally immiscible systems, such as Cu-V [1], Cu-W [2][3][4], Ag-Cu [5], Cu-Mo [6], Cu-Cr [7], Fe-Mg [8], Fe-Cu [9][10][11][12][13][14][15][16][17] etc. Under a thermodynamic equilibrium, Fe-Bi is virtually immiscible whether in a liquid state or in a solid state.…”