Effect Of Alloying And Modification On The Mechanical Properties Of Al-20Si Alloy

Compared with ordinary steel material, the hypereutectic Al-Si alloy has the advantages of low density, high specific strength, high ratio of mild and low coefficient of thermal expansion and wear resistance and other advantages. It's widely used in aerospace, automotive, high-speed trains, buildings, electronic products etc. However,with the increase of silicon content, the morphology of coarse primary silicon, long needle-like eutectic silicon, serious separation of the matrix and reduction the mechanical properties of the hypereutectic Al-Si alloy. Therefore, it is of great significance to study the mechanical properties of hypereutectic Al-Si alloy.The main contents and conclusions of this paper are as follows:In this paper,mainly study after addition the metal elements Mg, Ti, Mn, Cu, Ni, Bi,refinement modifier Al-P,rare-earth elements Ce and La in hypereutectic multicomponentAl-20Si alloy.By changing the content of Ni and Bi in hypereutectic multicomponent Al-20Si alloy, when the alloy after T6 heat treatment, Research the change of microstructure influence on the mechanical properties of the alloy.Observed the microstructure of the hypereutectic multicomponent Al-20Si alloy by AFT-DC130 optical microscope.The experimental results show that the Bi element has little effect on the primary silicon of the alloy after the modification treatment,but can make the eutectic silicon spheroidization phenomenon in alloy. The Ni element can not only refine the eutectic silicon, but also can combine with other metal elements in the alloy form a network, long, bone-like and other irregular shape compounds. This compounds is Al3Ni, Al7Cu4Niand other Ni-rich metal compounds after the XRD analysis.The hardness of hypereutectic multicomponent Al-20Si alloy was tested by HVS-5 Vickers hardness tester.The results show that with the increase of Bi content, the hardness of alloy decreases gradually, while with the increase of Ni content, the hardness of the alloy shows a tendency to increase gradually.Using YDX- ? 9702 piezoelectric dynamometer to measure cutting force when the axial depth of cutting depth is 0.4mm and 0.8mm, the feed rate is 100mm/min,200mm/min,300mm/min, the spindle speed is 470r/min, 550r/min, 650r/min. The results show that the cutting force increases and then decreases with the increase of Ni content, while the surface roughness decreases with the increase of Ni content.The cutting forces of experimental alloys with Ni contents of 0.8% and 1.2% were calculated.Obtainthe coefficient of general formula cutting forceof alloy.General formula for the cutting force of the alloy as follows:The Ni content was 0.8%: =9.8 . .. B . Z (Unit/N)The Ni content was 1.2%: =9.8 . .. B.Z (Unit/N)The dry friction and wear experiments were carried out using MMW-1A configuration universal friction and wear tester, while the experiment force is 45N. the experiment speed is 300 r/min, persistent for 10 minutes. After weigh the lost weight by using a BS124S balance. The results show that,due to the self-lubricating effect of Bi element, with the mass percentage of Bi increasing from 0.0% to 1.5%, the friction coefficient decrease from 0.74 to 0.58 of the alloy, wear is reduce from 2.8 mg to 2.3 mg of the alloy. With the mass percentage of Ni increase from 0.4% to 1.2%, the hardness of the alloy increases, the friction coefficient decrease from 0.74 to 0.52 of the alloy, wear is reduce from 2.8 mg to 2.1 mgof the alloy, the wear resistance is improve of the alloy.The wear mechanism from adhesive wear to slightabrasive wear and fatigue wear,the wear resistance of the alloy is improve.