Development of iron-based composite materials through electromagnetic radiations in a domestic microwave oven

Abstract

Microwave hybrid heating, a novel technique, is used to develop iron-based alloy (SS316), SS316+10EWAC1004 (nickel-based), and SS316+10EWAC1004+5Cr₇C₃ composite castings. The domestic microwave having a frequency of 2.45 × 10³ MHz and a power of 0.9 kW, is used with a variable exposure time of microwave radiations. The microwave interaction procedure with the metallic powder is discussed to optimize the exposure time and temperature. A microstructure study of developed castings revealed the uniform melting of matrix and EWAC1004 with an identical dispersion of Cr₇C₃. The X-ray diffraction results revealed various intermetallic (Ni₃Fe, Ni₂Si, Cr₂Ni₃, MoNi₄, Fe₃Si, Fe₂Si, CrFeNi) and hard carbides (Fe₃C, Cr₃C₂, Cr₂₃C₆) phases. The maximum average micro-hardness is for the SS316+10EWAC1004+5Cr₇C₃ composite, followed by SS316+10EWAC1004. The established composite casting had a hardness of around 2 times that of the commercial SS316. The maximum density of 97% was found for Iron-based SS316-based. The grain size of microwave-processed SS316, SS316+10EWAC, and SS316+10EWAC +5Cr₇C₃ specimens is found to be 21 ± 4 µm, 18 ± 3 µm, and 17 ± 2 µm, respectively. It has been observed that reinforced phases hinder grain growth, and hence grain size reduces significantly. In comparison, commercial SS316 had a grain size of 31 ± 6 µm. The ASTM B-276 standard is used to determine pores that are of the order of 1.98%.