Microstructure evolution in CuZrAl alloys during ball-milling

The microstructure evolution during mechanical milling was studied in the CuZrAl system. The compositions lay on the two liquidus surfaces indicating different solidification processes in the three alloys. Cu(55 − x)Zr(35 + x)Al10 (x = 0; 5; 10 at.%) master alloys were produced by arc melting. After identification of the phases, the master alloys were milled for 25 h and amorphous/crystalline powders were synthesized. The master alloys contained Al21Cu28Zr51, AlCu2Zr, CuZr and traces of Cu10Zr7 phases in different volume fractions. The optimal milling time was determined to be 15 h based on the results of X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) examinations. The 5 h milled powder contained CuZr and Al21Cu28Zr51 phases, which diminished due to further milling resulting in amorphous matrix composite with nanosized Al21Cu28Zr51 phase. The thermal stability of the samples was investigated by DSC. The peak temperatures of the first crystallization process of the as-milled powders shifted as function of milling time and polynomial curves were fitted to the measured points.