Abstract: A method of treating a shape memory alloy to improve its various characteristics and to cause it to exhibit a two-way shape memory effect. A raw shape memory alloy having a substantially uniformly fine-grained crystal structure is prepared and then its crystal orientations are arranged substantially in a direction suitable for an expected operational direction, such as tensile or twisting direction or the like, in which the shape memory alloy is expected to move when used in an actuator after the completion of the treatment.

Abstract: The present invention employs a shape memory alloy that exhibits a two-way shape memory effect and that has a stress-strain property that, in a stress-strain diagram, the stress-strain curve comprises a gentler gradient portion extending with relatively small gradients and a steeper gradient portion extending with relatively great gradients. The shape memory alloy is operated in the region surrounded by the gentler gradient portion, the steeper gradient portion, a practical stress limit line, a straight line connecting the intersection of the practical stress limit line and a strain limit line near shape recovery completion on which the strain of the shape memory alloy reaches a specified value in a state close to the shape recovery completion and the point where the strain is zero at a low temperature in the stress-strain diagram.

Abstract: A method of treating a shape memory alloy to improve its various characteristics and to cause it to exhibit a two-way shape memory effect. A raw shape memory alloy having a substantially uniformly fine-grained crystal structure is prepared and then its crystal orientations are arranged substantially in a direction suitable for an expected operational direction, such as tensile or twisting direction or the like, in which the shape memory alloy is expected to move when used in an actuator after the completion of the treatment.

Abstract: A method of treating a shape memory alloy to improve its various characteristics and to cause it to exhibit a two-way shape memory effect. A raw shape memory alloy having a substantially uniformly fine-grained crystal structure is prepared and then its crystal orientations are arranged substantially in a direction suitable for an expected operational direction, such as tensile or twisting direction or the like, in which the shape memory alloy is expected to move when used in an actuator after the completion of the treatment.

Abstract: A valve including a wire-shaped element of shape memory alloy as its driving source. The wire-shaped element is mechanically associated with a valve element so as to undergo an elongation from its original length when the valve element is moved in a predetermined direction, which can be either a direction to open a valve port or a direction to close the valve port. A biasing device biases the valve element in the predetermined direction. When the shape memory alloy is not heated to its critical temperature, it undergoes an elongation due to the biasing device, allowing the valve element to close/open the valve port. On the other hand, when heated to its critical temperature or higher, the shape memory alloy exhibits the shape memory effect contracting to its original length, whereupon the valve element opens/closes the valve port.