ZZNAL4Y Modification of die-cast zinc alloy

Title: ZZNAL4Y Modification of die-cast zinc alloy Author: Wang Xiande Degree-granting units: Xiangtan University Keywords: zinc alloy;; alloying elements;; mechanical properties;; Microstructure Summary:

In China 三号 zinc-aluminum alloy (3.5% ~ 4.3% Al) found during the industrial applications, there are impurities in the alloy with higher levels of overall performance instability and other issues. In order to further improve its mechanical properties and maintain stable performance alloys, to meet the needs of industrial production, the status of research at home and Neodymium Magnets abroad, the alloys of this thesis the following research.

In the alloy on the basis of domestic ZZnAl4Y added silicon, manganese, boron, titanium and rare earth elements, optimize alloy performance. Use of medium frequency induction furnace and graphite crucible resistance furnace for melting of the alloy; the use of computer-controlled electronic universal testing machine testing tensile strength of the alloy; use of HR-150 Rockwell hardness testing machine and micro-hardness tester (HXD1000T) alloy hardness test; use JB30A impact testing machine test the impact toughness of alloy; with optical microscope, scanning electron microscopy, electron probe micro-analyzer test tools research and analysis of the alloy microstructure. Through the preparation of the specimens tested at room temperature mechanical properties and microstructure analysis, seeking the best elements in the alloy to add volume to obtain better performance of the die-casting zinc alloy.

The results showed that:

(1) silicon, manganese, zinc alloy elements in solid solution in a very small degree, manganese mainly hard and brittle manganese-rich phase exists mainly in the silicon single crystal silicon form. Silicon, manganese has the alloying effect, can be refined alloy, eutectic increased. Silicon, manganese was added to make ZZnAl4Y tensile strength and hardness of zinc alloy is greatly improved, but the ductility and impact toughness decrease more. When adding 0.06 ~ 0.1wt.% Si and 0.05 ~ 0.1wt.% Mn element ZZnAl4Y zinc alloy has good mechanical properties.

(2) zinc alloy elements added boron, boron compounds produced η phase as an effective heterogeneous nucleation, increasing the nucleation rate of the η phase, η phase has been refined to make primary. When the added amount of boron is 0.05wt.% When the preparation of the zinc alloy has good mechanical properties.

(3) adding titanium zinc alloy, the aluminum alloy of titanium compounds produced (TiAl_3, TiAl_2, etc.), titanium-zinc compounds (Zn_16Ti, Zn_8Ti, etc.) and ternary compounds, these compounds are beneficial to enhance the nucleation rate η , refinement matrix structure. As the Ti content increases, the tensile strength and zinc-aluminum alloy first increases and then decreases elongation at break; hardness first increased and then decreased; to reduce the impact http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets toughness decreased but not much. Titanium content of 0.04wt.% ~ 0.05wt.%, The test alloy to obtain better mechanical properties.

(4) rare earth elements in Al, Zn in the solid solubility is very small, rare earth elements in the alloy will be added to the solution and the solution of zinc alloy, aluminum and other elements to form compounds of complex composition (such as LaZn_13, LaZn_8, LaB_9 , LaB_6, LaB_4), these compounds can increase the nucleation rate of the η phase, refine the alloy, is conducive to alloy to improve overall performance. Degree Year: 2010