Macrostructure and Strength of the Al–Zn–Sn Composite Produced by Liquid-Phase Sintering of the Al–Zn Alloy and Pure Tin Powder Mixture

Abstract

Features of liquid-phase sintering compacts made of powders of the Al–10Zn alloy and tin of the PO 2 brand, as well as the influence of sintering modes on the structure and strength of forming antifriction composite of the (Al–10Zn)–40Sn composition, are studied. The porosity of the initial green compacts varies in a range of 5–18%. Compacts are sintered in a vacuum furnace under a residual gas pressure no higher than 10–2 MPa. The sintering temperature varies in a range of 550–615°C and corresponds to the partial wetting of aluminum with liquid tin. The sample holding time at a specified temperature is from 30 to 180 min. Structural studies show that the particle size of the aluminum and tin phases increases with an increase in the sintering temperature and holding time. The mechanical properties of sintered composites are determined by their compression testing. The samples are cut from the middle of sintered compacts. It is established that samples made of the (Al–10Zn)–40Sn sintered alloy possess high ductility and exhibit higher strength when compared with the Al–40Sn sintered composite with a pure aluminum matrix due to the more intense strain hardening of a matrix at a high deformation. It is found that sintered composites prepared from high-density green compacts subjected to preliminary low-temperature holding possess the highest strength. Based on the results, it is concluded that the liquid-phase sintering in a specified temperature range makes it possible to prepare (Al–10Zn)–40Sn composites with a bound aluminum matrix effectively preventing the strain localization in soft tin-based phase interlayers. The optimal sintering temperature should not exceed 600°C.