Investigation On In-situ TiB₂/2024Al Composite Prepared By Molten Salt Reaction

Aluminum alloy emerges from perpetual need for lighter weight, easiermachining, higher thermal conductivity and better shock absorbing in aerospace,aircraft, automotive, electronics and shipbuilding industries. While, low hardness andpoor wear resistance limit its application, composite material is prepared to solvethese shortcomings. In recent years, composite reinforced with in-situ particle getmore attention from researchers, there are many advantages in the preparation processof in-situ MMCs, like low cost, simplicity and thermodynamic stability. The inbornreinforcements can prove more beneficial for working at high temperature, and theyare uniformly distributed in the matrix, which is benefited from small size. There areno reactions at the interface between reinforcements and matrix, so the interface isclean, which is good for properties of materials.In these studies, we add K2TiF6and KBF4in2024aluminum alloy to preparecomposites reinforced by TiB2, the in-situ TiB2particle is synthesized by two fluoridesalts.We investigate the process parameters during the preparation and mechanicalproperties of composite. Results of the present studies are as follows:(1) We get fine structure when we add K2TiF6and KBF4salts in the matrix at750oCor800oC or850oC, and the structure of composite is finer when the addingtemperature is800oC. We investigate the influence of mole ratio of Ti and B onthe grain size, and the results show that the grain size of composite is finer whenthe proportion of Ti and B is1:2. The order of K2TiF6and KBF4adding in the melt effects microstructure of composite, when the two fluoride salts add together,the microstructure of composite is finer.(2) The in situ TiB2prepared by molten salt reaction is fine, it is about500nm. Itpresents three different morphologies, containing single hexagon, hexagonalprisms and ball-like agglomeration. There is no contaminant in the interfacebetween in situ TiB2and2024Al matrix.(3) The grain refinement of2024Al is resulted from rolling deformation. When therolling temperature is350oC, the tensile property is better. When the fluoride saltsare added together at800oC, and the proportion of Ti and B is1:2, composites getbetter mechanical properties, the tensile strength is274MPa, and the elongation tofailure is14.5%.