Development of Ecological Al-Al_3Fe Functionnally Graded Material

1997 Fiscal Year Final Research Report Summary

• Project/Area Number: 08650799
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Composite materials/Physical properties
• Research Institution: Kagoshima University
• Principal Investigator: FUKUI Yasuyoshi Kagoshima University, Faculty of Engineering, Professor, 工学部, 教授 (00117540)
• Project Period (FY): 1996 – 1997
• Keywords: Functionally Graded Material / Vacuum Casting / Intermetallic Compound / Material Testing / Tensile Properties / Law of Mixture

Research Abstract

Aluminum can scraps include small amount of steel cans unavoidably. It is difficult and costly to remove the steel cans perfectly and to refine the scrap. How do we remanufacture the scrap efficiently for a structural and component material from the viewpoint of ecology? This is the motivation of the present study. Considering the two phase diagram of aluminum-iron system, intermetallic compound of Al_3Fe is found first at aluminum rich side. Intermetallics are known as hard and brittle nature but, in general, they have a lot of unknown properties that are difficult to find out in references. Is it possible to manufacture Al-Al_3Fe functionally graded material (FGM) that takes advantage of the hardness and high melting point of Al_3Fe intermetallics? FGM is one of the new concept materials and has a graded composition to use each advantage and/or make up each disadvantage. I have proposed the centrifugal method as one of FGM manufacturing methods, which utilizes the difference of centr ipetal force between molten metal and hard particles. If the aluminum scraps including iron is applied to the centrifugal method, a kind of Eco-FGM of Al-Al_3Fe can be manufactured. However, the centrifugal method in the laboratory of an ambient condition holds a difficulty to adopt to the high viscosity and low heat capacity alloy melt. The vacuum centrifugal casting system is, thus, planed and designed to overcome the shortage of the former system. A new system is satisfactorily constructed and Al-Al_3Fe FGM of a thick-walled tube is manufactured from Al-10 mass pct Fe master alloy. The morphology of Al_3Fe intermetallic in the aluminum matrix is examined. Profiles of Al_3Fe grain are changed from granular to needle shape depending one the position in the radial direction of the FGM tube. The graded composition is also examined and is varied from pure aluminum at inside of the tube to 40 vol pct Al_3Fe at outer plane of the tube. The corresponding graded Young's modulus and thermal expansion coefficient of Al-Al_3Fe FGM are in the range from 71 to 99.5 GPa and from 25.5・10^<-6> to 21.3・10^<-6>/K,respectively. Tensile tests are done using thin standard specimen for which Al_3Fe grains are homogeneously distributed and the average value is about 28 vol pct Al_3Fe. Tensile strength of 86 MPa at 0.44 pct tensile strain and Young's modulus of 90 GPa are obtained. It is expected that the FGM must be a good wear resistant and heat resistant FGM.