Effects of Ag, Co, and Ge additions on microstructure and mechanical properties of Be-Al alloy fabricated by investment casting

Abstract

The effects of Ag, Co, and Ge additions on microstructure and mechanical properties of alloys fabricated by investment casting were studied. The results reveal that the trace metals 1.5wt.% Ag, 0.7wt.% Co, and 0.8wt.% Ge additions do not change the nucleation temperature of Be phase. However, the nucleation temperature of the Al phase decreases from 642 °C to 630 °C by DSC due to the Ge addition. The strength of the alloys sharply increases due to the dissolution of the Ag and Ge solutes into the Al phase and the Co into the Be phase characterized by SEM and EDS. Obviously, the strength of Be-Al-Ag-Co-Ge alloy is improved by the solution strengthening. Furthermore, a few Ag 3 Al particles contribute to the strength of the Al phase. Be-Fe-Al ternary intermetallic compounds which can effectively reduce the negative effect of an impurity element Fe on the mechanical properties of Be-Al alloys are also found by XRD and EDS.

Effect of Interfacial Strength on Mechanical Behavior of Be/2024Al Composites by Pressure Infiltration

“…Adding alloying elements to the aluminum matrix is an effective way to obtain a uniform and refined microstructure, while helping to improve the interfacial strength between beryllium and aluminum, such as adding Mg, Si, Ag, Ge, Ni, Sc, Zr, etc. [ 13 , 14 , 15 , 16 ] At the same time, our previous work shows that in addition to powder metallurgy, precision casting, laser melting, and other preparation methods [ 17 , 18 , 19 , 20 ], the self-exhaust pressure infiltration technique has been successfully verified as an effective method to prepare high-strength Be/Al composites with good interfacial bonding [ 21 ]. Therefore, we selected two kinds of beryllium powders with different morphologies produced by different processes as reinforcements to prepare qualified beryllium/aluminum composites by the pressure infiltration method.…”