Assume that an alloy of nickel with 2 wt. percent aluminum is cast and by metallographic examination, a dendrite arm spacing of 50 µ is observed. It is also determined that the composition difference between the center of an arm, and the midpoint between two arms is one percent. Estimate the time required for homogenization if the annealing temperatute is to be 1400°C and the compostion difference is to be reduced to one?tenth or its original value. Note: See Table 12.5.
What will be an ideal response?
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Indicate whether the statement is true or false.
Arc strikes outside of the weld groove ____.
A. will crack as the pipe expands and contracts with heat B. form hardness spots which strengthen the weld C. should be made as often as possible D. increase pipe durability by increasing the pipe flexibility around the weld area
Most (usually 80% or more) of soil potassium and calcium can be found in the form of ________
A) dissolved substances B) organic compounds C) structural components of minerals D) exchangeable ions
Which of the following statements about placing dimensions is true?
a. Dimension lines may be joined end to end with a line of the drawing. b. Avoid placing dimensions on the drawing. c. Leaders may be drawn horizontally if adjacent leaders are also drawn horizontally. d. Fraction bars should be inclined except where the text is not clear. e. Always include unit marks in machine drawings.