Investigation Of Several Mg-Based Amorphous Alloys And Their Composites

The (Mg_0.77Cu_0.12Zn_0.05Y_0.06)100-xZr（xx=0,1,2）alloys with2mm and5mm in diameter,(Mg_0.77Cu_0.12Zn_0.05Y_0.06)100-xTix（x=0,1,3）with2mm in diameter, and Mg₈₁Ni₈Zn₅Y₆with2mm、3mm、5mm in diameter were prepared by copper mold casting technique.Effects of Zr、Ti element on the phase constituent, microstructure and mechanicalproperties of alloys were investigated. The effects of casting size on the phase constituent,microstructure and mechanical properties of the Mg₈₁Ni₈Zn₅Y₆alloys were also studied.The results show that:The microstructure of the (Mg_0.77Cu_0.12Zn_0.05Y_0.06)100-xZrx（x=0,1,2）amorphousmatrix composites all consists of the gray matrix and crystalline phase. As the addition ofelement Zr, the size of the black acicular phase became smaller. The white massive CuZrcrystalline phase and CuZr2crystalline phase are generated with the addition of Zr element.At the same time, the white point-like crystalline phase of Mg12YZn disappeared. Thecompression fracture strength is improved due to the addition of Zr element, however, theplastic strain is reduced. The compression fracture strength of (Mg_0.77Cu_0.12Zn_0.05Y_0.06)100-xZr（xx=0，1，2）alloys with2mm in diameter are corresponding739.4MPa、875.4MPa、749.3MPa and the plastic strain are respectively16%、8%、12%. The compression fracturestrength of (Mg_0.77Cu_0.12Zn_0.05Y_0.06)100-xZrx（x=0,1,2） alloys with5mm in diameter arecorresponding526.7MPa、607.5MPa、512.7MPa and the plastic strain are respectively15%、0%、3%.The microstructure of the (Mg_0.77Cu_0.12Zn_0.05Y_0.06)100-xTix（x=0,1,3）amorphousmatrix composites all consists of the gray matrix and crystalline phase. As the addition ofelement Ti, The microstructure of alloy long cycle phase dimension, while crystalline phase increases. The compression fracture strength is improved due to the Ti addition,however, the plastic strain is reduced seriously The maximum compression fracturestrength of (Mg_0.77Cu_0.12Zn_0.05Y_0.06)99Ti alloy with2mm in diameter is713.8MPa and theplastic strain is6%.With the increasing of casting size, the microstructure of the Mg₈₁Ni₈Zn₅Y₆amorphous matrix composites change obviously，the size of the black acicular phasebecame smaller，the crystalline phase Mg2Cu、Mg、Mg₁₂ZnY_were observed. Thecompression fracture strength and the plastic strain are all declined obviously...