The Preparation Of Al-Cu-Fe Quasicrystal Particles And The Streng Thening Function Of That For ZL101Alloy

Al-Si alloy is often used as the good choice for internal combustion engine pistons andcylinders because of excellent performance, such as high wear resistance and fatigueresistance, good casting properties. However, traditional Al-Si alloy have not been meet theneeds ofdeveloped market and the main reason was primary coarseα-Al and eutectic Sifragmenting melt severely. These characteristics seriously affect comprehensive propertiesand machinability of the alloy. As a attractive material, quasicrystal prossesses some uniqueproperties such as high hardness, heat resistance and low surface energy, which quite favorsfor its application as a strengthening phase in Al-Si alloy. The article is based on the idea ofquasicrystal strengthening Al-Si alloy and design a kind of new aluminum matrix composites.It is of great importance for expanding its application and improving the comprehensiveperformance of Al-Si alloy.The Al63Cu25Fe12alloy has been prepared by aconventional casting technique. Themicrostructures of the as-cast and subsequently annealed samples were examined by opticalmicroscopy(OM),X-ray diffraction (XRD)and scanning electron microscopy(SEM). Thepaper studied the effects cooling rate and annealing treatment on microstructures and phaseschange of Al63Cu25Fe12alloy. Subsequently, the heat-treated Al63Cu25Fe12quasicrystal milledand selected100to200mesh powder added ZL101alloy by semi-solid addition method andstages stirring method. The paper studied the quasicrystalline particles impacted on ZL101alloy, and researched different extrusion pressure, pouring temperature on comprehensiveperformance of Al-Si alloy. The ingot which prepared by the best technology was processedby heat treatment and investigated the effect of heat treatment on microstructure andmechanical properties of composite material.The result showed that,during the entire casting process of Al63Cu25Fe12alloy, theorganizational structureswere diverse and at least three different phases were formed, theλ-Al13Fe4, the icosahedral quasicrystalline (IQC) and the β-AlFe(Cu).The various coolingrates led to the clear difference of phase in as-cast condition and the amount of IQC phasebecame high when the cooling rate was low.However， the results of annealing treatmentsshowed that the other phases in Al63Cu25Fe12alloy had the trend to a singlequasicrystalline phase.After Al63Cu25Fe12quasicrystalline particles addedto ZL101alloyusing stir castingmethod, the results showed that the shape of the primary α-Al phase changedfrom thelath-shaped to rose and slender needle-like eutectic Si was interrupted to some shortorganizations and distribution. Tensile strength, elongation, hardness of the compositematerial were189MPa,3.7%,62.2HB and improving16.7%,15.6%,21.48%relative to thebase alloy. When squeezing pressure100MPa and pouring temperature720℃were theoptimum mechanical properties of the alloy.The result of microscopic fracture analysisshowed that the fracture mode of aluminum matrix composites iscleavage fracture.The heat-treatment result show that the shape of slender needle-like eutectic Si becameto spherical or ellipsoidal.After heat treatment, mechanical properties of the composites havea greatly improvement, the tensile strength wasfrom230MPa up to308MPa, improved34.6%;the hardness increased from74.5HB to110.4HB, improved by48.2%, the elongation rate of8.4%increased to10.5%.