Microstructure And Properties Of Mg-Cu Amorphous Alloys Fabricated By Mechanical Alloying

Amorphous Alloys have been used as superconducting materials, hydrogen storage materials, high-resistance materials, constant flexibility, constant thermal expansion material because of their excellent properties such as high strength, high toughness, high hardness and high wear-resistance. Since 1990s, high-strength amorphous Mg alloy is attaching more and more importance for its potential industrial application prospect and becomes one of the most important highlight in the research field of new materials.Mg₅₈Cu₄₂ and MgCu₂ amorphous alloys were prepared by the method of mechanical alloying. The influence law of the alloy microstructure, glass-forming ability and thermal properties affected by the technical parameters, alloy composition is studied by using X-ray diffraction and differential thermal scanning calorimeter. Based on the control of the shape of the amorphous and crystallization process, the paper studies the crystallization of amorphous alloys, supporting access to more comprehensive outstanding performance of nanocrystalline materials.MgCu₂'s glass forming ability is better than Mg₅₈Cu₄₂'s, which indicates that glass forming ability is related to the mixed powder. After 110 hours'interrupted milling, Mg₅₈Cu₄₂ has been transformed into amorphous. Different rotation speed of 200r/min,250r/min,300r/min are adopted in the milling experiment while the other parameters keep same. The results show that the best grinding effect comes from the experiment in which otation speed of 300r/min is selected. When material ratio is 20 to 1, the ball has enough free motion degree and alloying rate is faster and more sufficient. With continuous improvement and optimization, 1.5 percent of the ethanol process control agent is added which lead to higher extraction rate, refining powder and fewer impurities.Furthermore,with this method, mechanical alloying of powder can be realized. The results which are analyzed on thermodynamics and dynamics imply that amorphous's formation is derived from over-saturated solution's change from the instability conversion without nuclear and nuclear-up process process. For Mg-Cu amorphous alloys prepared mechanical alloying, a two amorphous structure of relaxation exothermic peak appeared when the room temperature get 600℃. At structure relaxation period, atom receives some energy and carries on the structure adjustment. At the same time, the former energy reduces and stress is released stress and strain is eliminated. These are the structural preparation for crystallization. When temperature keeps rising, there is a small heat-peak which is a non-Jingjing of the former energy to overcome the barrier and absorb heat. Once the peak jumps over, non-Jingjing reaction will occurs. Characteristic temperatures (Tg,Tx,Ts,Tm) all move to the high place with the temperature increase whichex plains thatcrystallization process is a dynamic process which depends on heating rate. Mg,Cu,B's mechanization is faster than Mg,Cu's which illustrates that mechanical alloying can speed up Mg and Cu's solution in Cu. Annealing treatment to the sample after milling causes the crystallization of amorphous alloys and the precipitation of nano-grain.