Effects of Vibration and TiB 2 Additions to the Melt on the Structure and Strain-Rate Sensitive Deformation Behavior of
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https://doi.org/10.1007/s11837-020-04339-6 Ó 2020 The Minerals, Metals & Materials Society
ALUMINUM AND MAGNESIUM: CASTING TECHNOLOGY AND SOLIDIFICATION
Effects of Vibration and TiB2 Additions to the Melt on the Structure and Strain-Rate Sensitive Deformation Behavior of an A356 Alloy MARINA G. KHMELEVA,1 ILYA A. ZHUKOV,1 GENNADY V. GARKUSHIN,2 ANDREY S. SAVINYKH,2 ANTON P. KHRUSTALYOV ,1,3 and ALEXANDER B. VOROZHTSOV1 1.—National Research Tomsk State University, Tomsk, Russia 634050. 2.—Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow region, Russia 142432. 3.—e-mail: [email protected]
For the first time, joint experiments have been conducted with samples of A356-TiB2 cast aluminum alloy under quasi-static and plane shock-wave loading. Alloys were obtained by introducing TiB2 particles using a masteralloy, combined with the effect of vibration treatment on the melt in order to fragment the dendritic structure and prevent its branching during solidification. The melt treatment and introduction of TiB2 particles allowed the average grain size to reduce to a third of that of the base cast alloy. During the experiments the strain rate and the shock-wave compression pressure were varied. It was shown that introducing particles affected the strain-rate sensitivity of the alloy. The best elastic–plastic and strength characteristics at increased strain rates of over 0.01 s1 were demonstrated by an A356 alloy without TiB2 particles.
INTRODUCTION Cast aluminum alloys of the Al-Si system are widely used due to their mechanical properties. The maximum values of strength and yield stress for these alloys are achieved by complicating and refining their chemical composition, reducing their grain size by treatment of the melt and creating a favorable internal stress state by heat treatment.1–3 Introducing ultrafine and nanoscale particles into the melt is a promising technique for creating materials with a heterophase structure. The morphological structure of the particles and interfacial interactions at the boundaries determine the physical and mechanical behavior of the final material. Due to similar parameters of their crystal structure, inoculants are able to act as supercooling centers in the melt during its solidification.4 A widely used modifier for aluminum alloys is titanium diboride (TiB2) being introduced ex situ using the Al-5Ti-1B master alloy4–6 or synthesized in situ by means of K2TiF6 and KBF4 salts.7 The optimal size of TiB2 (Received June 3, 2020; accepted August 17, 2020)
particles for this use is from 1 lm to 5 lm.8 For dispersion strengthening of alloys, that follow the Orowan mechanism, it is necessary to use particles up to 500 nm in size, such as Al2O3,9,10 SiC,11 and others. TiB2 can also be used for dispersion strengthening of an aluminum matrix due to its high mechanical properties.12 The introduction of particles with a size distribution in the range 500 nm to 1.5 lm may allow structural modification due to grain refinement of the alloy and dispersion
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