Effect of solidification parameters on microstructural characteristics and mechanical properties of directionally solidified binary TiAl alloy

• Microstructure and mechanical property of DS Ti–49Al alloy was investigated.
• Values of λ1 and λL decrease with increasing cooling rate.
• The values of HV and σ increase with increasing cooling rate.
• The values of HV and σ decrease with increasing λ1 and λL.
• Experimental correlation between tensile strength and microhardness was established.

Microstructural characteristics and mechanical properties of Ti–49Al (at.%) alloy was investigated by directional solidification technology under different solidification parameters in a Bridgman-type furnace. Variations of primary dendritic arm spacing, interlamellar spacing and mechanical property with solidification parameters were investigated. The values of primary dendritic arm spacing and interlamellar spacing decrease with increasing cooling rate. Values of microhardness and tensile strength increased with the increase of cooling rates, and decreased with the increase of primary dendritic arm spacing and interlamellar spacing. The relationships between the primary dendritic arm spacing, interlamellar spacing, microhardness, tensile strength and cooling rate are proposed. The tensile strength of directionally solidified Ti–49Al (at.%) alloy increases with the increase of microhardness. There is a linear correlation between microhardness and tensile strength of the directionally solidified TiAl alloy. The experimental correlation between tensile strength and microhardness was established. The results were further compared with previous similar experimental results.

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