Definição

• Space Metal.  A new metal alloy formulated in space, outside the gravity restrictions of the earth. While we can only speculate on the physical characteristics of space metals now in the 21st century, it is inevitable that new alloys will be formed in space shortly. Gold, as heavy as it is, cannot be alloyed with light-weight aluminum on earth. And despite the term nickel-silver (actually a bronze alloy) nickel and silver are not a compatible alloy – they cannot be alloyed on earth. (Such mixtures are called noncompatible alloys.) Another is lead and zinc.
  Could these alloys be formulated in space, and if so, what metallurgical characteristics would these and other new alloys posses? It is obvious a medal could be fabricated in any of these alloys no matter what physical properties they posses. (In the article on medallic object the author predicts that the organization that produces the first medal of space metal will reap a fortune.) But metallurgists might find uses for a space alloy what could be beyond our expectations. Say, a new coinage alloy from space perhaps. See alloy, composition (2).
  Spalling.  Minute chips of metal driven off the face of a die by stress during continued striking. Dies with a brittle surface are more likely to chip with small, thin flakes than those with a good tempering.  Coins struck from such a die will either exhibit irregular raised areas, usually near the edge, or within detailed parts of the design where the die is weakest.
              Working dies are subject to significant mechanical stress during constant striking. This amplifies minute discontinuities with metal crystal defects until the die cracks or deforms. The most common die defects not related to damage were spalling, cracking, chipping, and collapse. Cracks in dies are commonplace resulting from a combination of imperfect annealing and tempering of the steel plus excess mechanical stress on the weakest parts of a die.
                                     
  Dies that were excessively brittle at the surface were more likely to spall than those with a good tempering. Chipping refers to thin flakes or millimeter-size pieces of the die surface that fall out of a working die. Coins struck from a chipped die will either have irregular raised areas, usually within detailed parts of the design where the die is weakest, or rough elliptical raised areas. See DIEBREAK.
  CLASS 06.9
  6745-(009)04.3           Illus: Photo: microphoto

  excerpted with permission from

  An Encyclopedia of Coin and Medal Technology

  For Artists, Makers, Collectors and Curators

  COMPILED AND WRITTEN BY D. WAYNE JOHNSON

  Roger W. Burdette, Editor

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