การพัฒนาโครงสร้างจุลภาคและสมบัติทางกลของโลหะผสมเงิน-เบริลเลียมเกรด 935

• Main Author: ตระกูลศักดิ์ สุขรี
• Other Authors: เอกสิทธิ์ นิสารัตนพร
• Format: Theses and Dissertations
• Language: Thai
• Published: จุฬาลงกรณ์มหาวิทยาลัย 2006
• Subjects: โลหะผสม; โครงสร้างจุลภาค; โลหะผสมเงิน-เบริลเลียม; โลหะผสมเงิน-เบริลเลียม > สมบัติทางกล
• Online Access: https://digiverse.chula.ac.th/Info/item/dc:44974
• Institution: Chulalongkorn University

The objective of this work is to study the effects of beryllium and heat treatment, including temperature and time in solid-solution treatment and in aging, on macrohardness, mechanical properties and microstructure of the cast alloy 93.5 wt%Ag, 6.37 wt%Cu and 0.13 wt%Be, comparing to those of the cast alloy 93.5 wt%Ag and 6.5%Cu without beryllium addition. The results revealed that beryllium increased the maxima of macrohardnes and the mechanical properties obtained after aging. The macohardness of the Ag-Cu-Be alloy, after solid-solution treatment at 750 degree celsius for 60 minutes and quenching in cold water at 10 degree celsius, was 58 HV with the yield stress 60.95 MPa, elastic modulus 13.75 GPa and the modulus of resilence 135.08 KPa. Consequently aging resulted in an increase of the marcohardness and the mechanical properties. The maximum macohardness value was 162 HV with the yield stress 339.70 MPa, elastic modulus 59.19 GPa and the modulus of resilence 974.79 KPa after aging at 350 degree celsius for 30 minutes. Comparing to the Ag-Cu with no beryllium addition, the macrohardness after solid-solution treatment at the same condition was 61 HV with the yield stress 73.35 Mpa, the elastic modulus 17.91 GPa and the modulus of resilience 150.20 KPa. After aging at 300 degree celsius for 60 minutes, the maximum value obtained was only 136 HV, 224.06 MPa, 44.45 GPa and 564.71 KPa, respectively. Regarding to the microstructure, beryllium had an effect on modifying of the eutectic structure from the typical, parlite-like lamellar in the Ag-Cu alloy without beryllium addition to a structure with more sphericity in the Ag-Cu-Be alloy. The reason for an improvement in the macrohardness and the mechanical properties after aging in the case of the alloy with beryllium addition is possibly due to a fine precipitation within the primary phase. The likely explanation for higher macrohardness and the mechanical properties in the Ag-Cu alloy with no beryllium addition after solution treatment and subsequently water-quenching is the higher quantity of copper and the lesser dissolution of the eutectic structure into the matrix. However, when considering the properties and the microstructure after aging, the cast alloy 93.5 wt%Ag, 6.37 wt%Cu and 0.13 wt%Be is superior for applications such as spring in jewelry.