On Selenium Whiskers

It has been found that Se whiskers grow on Mg and its alloys with Al and Zn immersed in an aqueous solution of selenious acid (H2SeO3), and the effects of the concentration of the solution and of the alloying elements on the whisker growth were studied under a metallurgical microscope and by X-ray analysis. Some whiskers appeared first on Mg or its alloys immersed in the solution for 20∼30 minutes, and after 1∼5 hours the number of the whiskers increased remarkably. Then, the whisker growth retarded and stopped after 24 hours. The time required for the growth of each whisker was 30∼120 seconds. In 2% solution whiskers hardly grew, and in 4% solution the number of the whiskers increased remarkably, but in more concentrated solutions the number of the whiskers remained almost the same. With increasing content of Zn and Al up to 8%, the number of the whiskers and their sizes became larger, while the whiskers hardly grew on Mg-40%Al alloy. The maximum length of the whiskers was 2 cm. The whiskers had round pipe-like section and their diameter was 0.1∼0.01 mm. The crystal structure of the whiskers is hexagonal and each whisker is not a single crystal but a polycrystal.