Linear Thermal Expansion and Specific Heat Capacity of Cu-Fe System Laser-Deposited Materials

Abstract

The coefficient of linear thermal expansion and the specific heat capacity of laser-deposited Cu-Fe alloys fabricated from tin, aluminum, chromium bronze (89–99 wt.% Cu), and SS 316L were studied. The investigated alloys had a 1:1 and a 3:1 bronze–steel ratio. The Al–bronze-based alloy showed the lowest value of linear thermal expansion coefficient: (1.212 ± 0.095)∙10−5 K−1. Contrarily, this value was the highest {[(1.878–1.959) ± 0.095]∙10−5 K−1} in the case of functionally graded parts created from alternating layers of bronze and steel. Differential scanning calorimetry provided experimental results about the specific heat capacity of the materials. In the case of Al–bronze-based specimens, it demonstrated a decrease in the specific heat capacity until ~260 °C and its further increase during a heating cycle. Exothermic peaks related to polymorphic transformations were observed in the Al–bronze-based specimens. Cooling cycles showed monotonous behavior for specific heat capacities. It had exothermic peaks in the case of Cr–bronze-based alloys. A Lennard-Jones potential equation was used for testing the relation between heat capacity and thermal expansion. A three-way interaction regression model validated the results and provided the relative thermal expansion of commercially pure DED-fabricated SS 316L. Its specific heat capacity was also studied experimentally and was 15–20% higher in comparison to the traditional method of production.

Keywords

• direct energy deposition (DED)
• Cu-Fe
• coefficient of linear thermal expansion (CLTE)
• functionally graded materials (FGMs)
• specific heat capacity
• differential scanning calorimetry (DSC)