Page 70 - MSAM-3-2

Materials Science in Additive Manufacturing Mechanical properties of NiTi TPMS

value recorded was 477.8 HV for A10, representing a slip in the matrix increases, leading to an overall increase
71.74% increase compared to the untreated samples. This in hardness. In addition, the precipitation of the NiTi
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2
notable increase can be attributed to the precipitation of phase also contributes to the improved hardness of the
the second phase, which enhances the resistance to plastic sample. Saedi similarly observed an increase in sample
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deformation. As a result, the critical stress required for hardness with extended aging time, underscoring the
significant influence of aging duration on the hardness of
NiTi alloy. Moreover, it is worth noting that the hardness
of NiTi alloy is highly dependent on the test environment
temperature.
3.2. Effect of aging heat treatment on compressive
properties
The compressive stress-strain curves of RGCS and SGCS
after different aging times are depicted in Figure 6A and B.
Both structures exhibited three classical stages during the
compression process: (i) linear elastic stage, (ii) yield stage,
and (iii) fracture stage. During the initial stage, RGCS
underwent a brief period of linear elastic deformation
before transitioning into the yield stage. During the yield
stage, stress increased non-linearly until reaching the
strength limit, followed by a sharp stress drop leading to
sample failure. Following aging heat treatment, the yield
Figure 5. Microhardness of samples with aging heat treatment. plateau of RGCS structures extended, enhancing plasticity

A B

C D

Figure 6. Compression results of samples treated with different aging times. (A) The stress-strain curve of rod-shaped gyroid cellular structure (RGCS).
(B) The stress-strain curve of sheet-shaped gyroid cellular structure (SGCS). (C) Elastic modulus. (D) Compressive strength.

Volume 3 Issue 2 (2024) 7 doi: 10.36922/msam.3137