Preparation And Properties Of Zr-based Amorphous Alloy Studied

Zr-based bulk amorphous alloys have stronger glass forming ability and wider supercooled liquid region, which can be easily prepared bulk amorphous alloys with excellent properties. At the same time, Zr-based bulk amorphous alloys have a series of excellent mechanical properties. Thus, Zr-based bulk amorphous alloys are one of the amorphous alloy systems which mostly studied at present and has a very wide application prospect.So, Zr-based bulk amorphous alloys are one of the hot spot of material research fields.In this paper, Zr-Cu binary,Zr-Cu-M ternary,Zr-Cu-Al-Re quaternary and Zr-Cu-based quinary bulk amorphous alloys were prepared by adding minor Al,Ni,Ti and rare earth elements (Y,Gd) into binary Zr-Cu system.Bulk amorphous alloy rods with different diameters were prepared with copper.mold suction casting and copper mold spray casting, and we studied preparation process of bulk amorphous alloys. And the glass forming ability of different systems were examined by XRD, DSC respectively. Alloy properties and influence factors were studied by observing microstructures,fractures and mechanical properties tests.The main experimental results and conclusions are listed as follows:Firstly, The glass forming ability of Zr-Cu binary and Zr-Cu-M ternary bulk amorphous alloys was relatively weak. The microstructures of samples were studied by SEM and OM. The results showed that, the alloys were composed of amorphous and a little crystallization basically.Secondly,the glass forming ability and thermal stability of Zr47_xCu46Al7Yx(x=4～7),Zr48-xCu45Al7Gdx(x=2,3),Zr42Cu46Al7Gd5 bulk amorphous alloy rods were studied. The results showed that, in the Zr-Cu-Al-Re(Re=Y, Gd)BMG alloys,△Tx was between 56and79, Trg was in the range of 0.662～0.698,which indicate that the glass forming ability and thermal stability of samples were improved. And we also came to the conclusion that the glass forming ability of amorphous alloys prepared by copper mold spray casting was stronger than that prepared by copper mold suction casting and smaller diameter with stronger glass forming ability.The microstructures of different samples were studied by SEM and optical microscope. The results showed that, the microstructures of BMG alloys well distributed and exhibited typical organizing feature of BMG alloys.Thirdly, the vickers hardness of Zr-Cu-Al-Re(Re=Y, Gd)was examined by micro vickers. The results showed that, in the Zr47-xCu46Al7Yx(x=3～7)systems alloys, The Vickers hardness values exhibited some fluctuation with the addition of Y element. The highest hardness value was 513 when adding Y with 7at.%. The hardness values of BMG alloys displayed obviously differences when they were prepared by different preparation processes and different copper mold diameters, which indicated that the hardness of the same kind of BMG alloys had a direct relation with preparation processes and diameters. In the Zr45Cu45Al7Gdx(x=2,3),Zr42Cu46Al7Gd5 BMG alloys, the vickers hardness values showed a decreasing tendency with the addition of Gd element.Finally, compressive property and fracture morphology of Zr-Cu-Al-Re(Re=Y, Gd)BMG alloys were examined. The results showed that, in the Zr47-xCu46Al7Yx (x=4～8) systems alloys, compressive strength was increased with the addition of Y element. While in the Zr45Cu45Al7Gdx(x=2,3). Zr42Cu46Al7Gd5 BMG alloys, compressive strength was decreased with the addition of Gd element. Sample did not have obviously plastic deformation. All of the fracture forms were typical brittleness fracture, fracture surface showed vein-like pattern. And all the deformations occurred in the shear bands.