Microstructural Evolution and Mechanical Properties in Directionally Solidified Sn–10.2 Sb Peritectic Alloy at a Constant Temperature Gradient

Elif Yılmaz,Emine Acer,Mehmet Gündüz,Emin Çadırlı

doi:10.1590/1980-5373-mr-2015-0104

Elif Yılmaz, Emine Acer + Show 2 more

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https://doi.org/10.1590/1980-5373-mr-2015-0104

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Abstract

The Sn–10.2 Sb (mass fraction) peritectic alloy was prepared using a vacuum melting furnace and a hot filling furnace. The samples were directionally solidified upwards at steady state conditions with a constant temperature gradient (G=4.5±0.2 K. mm-1) under different growth velocities (V=13.3–266.7 µm. s-1) in a Bridgman-type directional solidification apparatus. The effects of the growth velocity (V) on the dendritic spacings were investigated. Primary dendrite arm spacing (PDAS) of α phase in directionally solidified Sn–10.2 Sb peritectic alloy was measured on the longitudinal and transverse sections of 4 mm diameter cylindrical samples. Secondary dendrite arm spacing (SDAS) was measured on the longitudinal section. The experimental results show that the measured PDAS (λ1L, λ1T) and SDAS (λ2) decrease with increasing growth velocity. The dependence of PDAS, SDAS, microhardness (HV) and compressive strength (σc) on the growth velocity were determined by using a linear regression analysis. The experimental results were compared with the previous experimental results and the results of the experimental models.

Highlights

Peritectic solidification has attracted more attention in experimental and theoretical studies[1] since many technologically important materials are peritectic, such as Sn–Cd2,3, Sn–Sb4,5, Sn-Ag6, Sn–Bi–Zn7, Zn–Cu8,9, Zn–Ag10 lead-free soldering materials, high temperature intermetallics Ti–Al11, Ni–Al12, HF–B13, superconducting materials YBCO14, magnetic materials Nd–Fe–B15, and structural materials Fe–Ni16,17 and Fe–Cr–Ni18
The aim of the present work is to study the effect of growth velocity on Primary dendrite arm spacing (PDAS), Secondary dendrite arm spacing (SDAS), microhardness (HV), and compressive strength for a directionally solidified Sn–10.2 Sb peritectic alloy using the Bridgman method at a constant temperature gradient (G=4.5 K. mm-1), and to compare the results with the previous experimental results for similar alloy systems
Increasing of growth velocity was observed to result in finer microstructures

Summary

Introduction

Peritectic solidification has attracted more attention in experimental and theoretical studies[1] since many technologically important materials are peritectic, such as Sn–Cd2,3, Sn–Sb4,5, Sn-Ag6, Sn–Bi–Zn7, Zn–Cu8,9, Zn–Ag10 lead-free soldering materials, high temperature intermetallics Ti–Al11, Ni–Al12, HF–B13, superconducting materials YBCO14, magnetic materials Nd–Fe–B15, and structural materials Fe–Ni16,17 and Fe–Cr–Ni18. Many interesting microstructures have been found during directional solidification of peritectic alloys, which have drawn much attention since the last four decades[4]. In the solidification of these alloys, a dendrite structure is the commonly encountered pattern. The microstructural scales involving the primary dendrite arm spacing (PDAS) and the secondary dendritic arm spacing (SDAS) have been carried out in directional solidification of various peritectic alloys, including Pb–Bi19, Zn–Cu19 and Nd–Fe–B20. PDAS and SDAS in the solidification microstructure determine the final physical properties of peritectic alloys. It is of great significance to control the peritectic solidification by different techniques (Bridgman method[6,7], Forced Crucible Rotation[21], Bridgman-Stockbarger[22], Ultrasonic Vibration , 5,23 Temperature Gradient Zone Melting[24])

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