Influence of the Content of Ni as Minority Alloying Element on the Microstructure and Mechanical Properties of Amorphous and Ultrafine Crystalline Al-Cu-Mg-Ni Alloys

Abstract

The effect of nickel as a minority alloying element (1--3) at.% on the structure and mechanical properties of amorphous and ultrafine crystalline Al⁷⁵Cu¹⁵Mg⁹Ni, Al⁷⁵Cu¹⁵Mg⁸Ni² and Al⁷³Cu¹⁵Mg⁹Ni³ alloys was investigated. Rapidly solidified ribbons of the three alloys were produced by chill block melt spinning (CBMS) method. It was proven that the rapid solidification produced amorphous structure in all alloys. Detailed HRTEM observations revealed zones of chemical inhomogeneity in the X-ray amorphous matrix which were identified as zones containing clusters of different atoms. A part of the ribbons was annealed until complete crystallization. The indentation hardness H_IT and indentation modulus E_IT of the amorphous and ultrafine crystalline Al-Cu-Mg-Ni alloys were investigated and compared using nanoindentation tests. The obtained results showed an increase of H_IT and E_IT with increasing Ni content in both amorphous and ultrafine crystalline samples. All ultrafine crystalline samples had higher H_IT and E_IT than the amorphous ones.