小角度晶界對(duì)DD5鎳基單晶高溫合金力學(xué)性能的影響

小角度晶界對(duì)DD5鎳基單晶高溫合金力學(xué)性能的影響Effect of Low Angle Grain Boundaries on Mechanical Properties of DD5 Single Crystal Ni-base Superalloy

采用籽晶法制備了二代鎳基單晶高溫合金DD5小角度晶界試樣，研究小角度晶界對(duì)DD5合金力學(xué)性能的影響。結(jié)果表明：在870 ℃中溫拉伸中，晶界角度小于16.1°時(shí)，合金抗拉強(qiáng)度和屈服強(qiáng)度無(wú)明顯變化；晶界角度小于11.4°時(shí)，伸長(zhǎng)率維持在15%以上；晶界角度大于11.4°后，伸長(zhǎng)率開(kāi)始快速下降；在980 ℃/250 MPa 持久條件下，當(dāng)晶界角度小于5.1°時(shí)，持久壽命維持在140 h以上；當(dāng)晶界角度大于5.1°時(shí)，持久壽命隨晶界角度增大開(kāi)始緩慢下降，至14.8°時(shí)，持久壽命仍保持為原來(lái)的85%；當(dāng)晶界角度大于14.8°后持久壽命開(kāi)始快速下降；在1093 ℃/158 MPa持久條件下，當(dāng)晶界角度小于5.1°時(shí)，持久壽命維持在30 h以上；當(dāng)晶界角度大于5.1°時(shí)，持久壽命隨晶界角度增大而下降。

The effects of low angle grain boundaries on the mechanical properties of second generation single crystal superalloy DD5 were investigated and the test specimens were prepared by using seeds. The results show that at 870 ℃, the yield strength and breaking strength showed no difference when the angle is below 16.1°. The elongation is higher than 15% when the angle is below 11.4°, but the elongation decreases quickly when angle is above 11.4°. At 980 ℃/250 MPa, the rupture life is higher than 130 h when the angle is below 5.1°, and decreased slowly when the angle is above 5.1°. The rupture life still remaines 85% when the angle is 14.8°. But the rupture life decreases quickly when the angle is above 14.8°.At 1093 ℃/158 MPa, the rupture life is higher than 30 h when the angle is below 5.1°, and decreases when the angle is above 5.1°.

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