Importance of Grain Growth
Most materials exhibit the Hall–Petch effect at room-temperature and so display a higher yield stress when the grain size is reduced. At high temperatures the opposite is true since the open, disordered nature of grain boundaries means that vacancies can diffuse more rapidly down boundaries leading to more rapid Coble creep. Since boundaries are regions of high energy they make excellent sites for the nucleation of precipitates and other second-phases e.g. Mg–Si–Cu phases in some aluminium alloys or martensite platlets in steel. Depending on the second phase in question this may have positive or negative effects.
Read more about this topic: Grain Growth
Famous quotes containing the words importance of, importance, grain and/or growth:
“More than ten million women march to work every morning side by side with the men. Steadily the importance of women is gaining not only in the routine tasks of industry but in executive responsibility. I include also the woman who stays at home as the guardian of the welfare of the family. She is a partner in the job and wages. Women constitute a part of our industrial achievement.”
—Herbert Hoover (1874–1964)
“Coming together again after a long day apart can be an experience where joy, relief, anger, and fatigue are all present in different degrees both for the parent and for the child. Because of their importance in marking the resumption of direct contact, reunions deserve as much attention and care as separations to enhance the relationship between parent and child.”
—Alicia F. Lieberman (20th century)
“Indigenous to Minnesota, and almost completely ignored by its people, are the stark, unornamented, functional clusters of concrete—Minnesota’s grain elevators. These may be said to express unconsciously all the principles of modernism, being built for use only, with little regard for the tenets of esthetic design.”
—Federal Writers’ Project Of The Wor, U.S. public relief program (1935-1943)
“From infancy, a growing girl creates a tapestry of ever-deepening and ever- enlarging relationships, with her self at the center. . . . The feminine personality comes to define itself within relationship and connection, where growth includes greater and greater complexities of interaction.”
—Jeanne Elium (20th century)