| Because of high melting point, high strength and good high temperature oxidation resistance, AB2 type Laves intermetallic causes concern of researchers.But,with other intermetallic compounds,Laves phase is brittle at room temperature. This limits its application and development largely. Recently, main research is focused on phase transformation, plastic deformation mechanism and strutural defect of Laves phase intermetallics and it is main problem to find the way to overcome the brittleness.In this paper, decreasing brittleness was studied from the stoichionetric ratio and alloying.1. In the MgCu2 solid solution scope, Laves phase MgCu2 was prepared by the method of mechanical activation combining with hot pressing. In order to analyse the defect strutures of MgCu2 Laves phase, lattice constants were calculated by XRD and density was measured by Archimedes drainage method. In addition, the enthalpy of formation was considered. The results showed that anti-site defects exists in the non-stoichiometric MgCu2 Laves phase. A maximum hardness and a minimum flexural strength occur near the stoichiometric composition. When the composition deviates from the stoichiometry, the hardness decreases and the flexural strength increases. The presence of anti-site defects results in softening effect in the MgCu2 Laves phase. Meanwhile, the brittleness of the compound decreases when the composition deviates from the stoichiometry.2. The AB2 Laves phase Mg(Cu1-xNi)2(0.05≤x≤0.35) was prepared with the method of mechanical activation combining with hot-pressed sintering. The phase, micro-morphology, and mechanical properties of hot-pressed products were analyzed. The results showed that, although part of the Cu atoms in MgCu2 are substituted by Ni, the crystal structure is not changed, and the main phase is still the C15 structure (MgCu2 type) Laves phase. After adding Ni, Metallographic organization is more uniform,and the relative density is higher.With the increase of Ni content, the diffraction peak shift to the high angular position and the lattice constant gradually decreases. At the same time, with the increase of Ni content, the hardness increases, and the compressive strength and the flexural strength increase first and then decrease. The compressive strength and the flexural strength of Mg(Cu1-xNi)2(x=0.15) are largest. Using the element Ni for alloying, it can effectively improve ductility of MgCu2 Laves phase. 3. The AB2 Laves phase Mg(Cu1-xSi)2(0.05≤x≤0.20) was prepared with the method of mechanical activation combining with hot-pressed sintering. The phase, micro-morphology, and mechanical properties of hot-pressed products were analyzed. The results showed that, after adding the element Si, the crystal structure is not changed, and the main phase was still the C15 structure (MgCu2 type) Laves phase. At the same time, metallographic organization is more uniform, and the relative density is high.With the increase of Si content, the hardness increased largely, and the compressive strength and the flexural strength increased first and then decreased. The compressive strength and the flexural strength of Mg(Cu1-xSi)2(x=0.10) are largest.
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