Pilot Study The Microstructure And Properties Of Expansion Alloy 4J43

Expension alloy 4J43 is belonged to the precious alloy, it is used for core alloy of the Dumet wire. Because of the steady coefficient of expansion, it is widely applied to leads for electron devices in metal to glass seals. But there is no other suitable substitute material to be found at present. While there is not so much articles and papers of 4J43 alloy to be reported all over the word. So it is very significative to research the microstructure and properties of 4J43 alloy.In this paper, basic theory and correlation report of the 4J43 alloy were introduced. Based on this, the microstructure and properties of the 4J43 alloys in different section is researched, which was produced by three different processes. And the surface defect of the 4J43 alloy has been investigated.The results indicate that though the cost is low and productivity is high for the first process, developed columnar crystals, transcrystalline, serious component deviation and center rarefaction of central rods exist in cast rods. These cast deficiencies must have a rather big effect on quality of following press working. The second process solves the problems of coarse columnar crystals and central rarefaction existed in the first process. Without the second-refine process in the two processes, the contents of non-mental impurities in finished product of 4J43 alloys are high, so making the quality of 4J43 alloys is low. The third process solves the problem of removing gas and dreg, decreasing component deviation. But surface quality of alloy produced by the third process is exists stripes in surface of product and Φ12 rods along axial direction and that can be seen by naked eyes.After analysis, surface defects in surface of 4J43 alloy rod is crack, plenty of hard nonmetallic inclusions, which exists in interior and surface of rods, during the procedure of after rolling and dragging, the deforming value of nonmetallic inclusions is smaller than substrate, causing stress concentration lies in interface between nonmetallic inclusions and substrate, so inducing the generation of tiny crack. These nonmetallic inclusions is composite, mainly consists of Si,Al, C,O and Ca elements and so on, aluminum oxide silicate, calcium aluminate and calcium silicate.