Effect of Structural Transformation on the Creep Parameters of Sn–9.8 wt% In Alloy

The low melting point of Sn–In alloys opens them a broad field of industrial applications, especially as Pb free solders. Sn–9.8 wt% In alloy is investigated for its structure and creep behaviour. The X-ray diffraction analysis shows that the slowly cooled sample contains both the β-Sn phase and the intermetallic compound γ-InSn₄, while the quenched sample is only composed of the γ-phase. Tensile creep tests are performed under applied stresses of 13.4, 14.7, 16 and 17.3 MPa in the temperature range from 353 to 423 K. The investigated parameters show one transformation temperature (393 K). The strain rate sensitivity parameter m has values ranging from 0.156 to 0.165 in the low temperature range (353–383 K) and from 0.229 to 0.243 in the high temperature range (393–423 K). The activation energy Q is slightly affected by the applied stress and has average values of (35.8 ± 3.7) and (49.9 ± 1.5) kJ/mol in the low and high temperature ranges, respectively. Q and m values are compared and discussed in the light of the governing mechanisms.