Solidification of Alloys: Solidify over a range of temperature, Mushy zone, Columnar dendrites crystals

What category of materials were likely the first man-made materials?: A: Copper Alloys B: Ceramics C: Composites D: Concrete E: Semiconductors

The minimum hardness in the joint of a FSWed precipitation-hardened aluminum alloys lies in the （ ）. A: thermally affected zone B: thermomechanically affected zone C: dynamically recrystallized zone

3.3The following materials are widely used in high power machines except for . A: Unalloyed iron B: Nd2Fe14B permanent magnetic materials C: Aluminum-iron alloys D: Silicon-iron